This reverts commit 1dc8695a.

Adds TextInputModel::SelectToBeginning/End() and applies when shift key is pressed.

This fixes an issue in CppWinRT related to std::terminate(); the tool
now uses abort() instead.

CppWinRT patch: https://github.com/microsoft/cppwinrt/pull/868

This also fixes a couple bugs in the README.md:
* Uses tmp as the temp dir into which we unpack the nupkg archive rather
  than cppwinrt to avoid confusion with the containing directory, which is
  named cppwinrt.
* Fixes a typo around the directory from which the cipd command should
  be executed.

https://github.com/flutter/flutter/issues/75500

This broke the Linux Web Tests target in the framework tests.

Example failure:
https://ci.chromium.org/ui/p/flutter/builders/try/Linux%20web_tests/11335/overview

Failure log:
```
01:09 +107 ~2 -1: test/widgets/rich_text_test.dart: WidgetSpan calculate correct intrinsic heights [E]
  Test failed. See exception logs above.
  The test description was: WidgetSpan calculate correct intrinsic heights

01:09 +107 ~2 -1: test/widgets/rich_text_test.dart: RichText implements debugFillProperties
01:09 +107 ~2 -1: test/widgets/rich_text_test.dart: RichText implements debugFillProperties
══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
The following assertion was thrown during performLayout():
Assertion failed: file:///b/s/w/ir/k/flutter/packages/flutter/lib/src/rendering/box.dart:2237:16
!RenderObject.debugCheckingIntrinsics
is not true

The relevant error-causing widget was:
  Text file:///b/s/w/ir/k/flutter/packages/flutter_test/lib/src/binding.dart:567:12

When the exception was thrown, this was the stack:
../dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 236:49  throw_
../dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 29:3    assertFailed
../packages/flutter/src/rendering/layer.dart.js 4485:79                          <fn>
../packages/flutter/src/rendering/layer.dart.js 4551:26                          debugAssertDoesMeetConstraints
../packages/flutter/src/rendering/layer.dart.js 4380:14                          <fn>
../packages/flutter/src/rendering/layer.dart.js 4382:26                          set size
../packages/flutter/src/rendering/paragraph.dart.js 786:17                       performLayout
../packages/flutter/src/rendering/layer.dart.js 3392:14                          layout
../packages/flutter/src/rendering/shifted_box.dart.js 451:36                     performLayout
../packages/flutter/src/rendering/layer.dart.js 3392:14                          layout
../packages/flutter/src/rendering/layer.dart.js 4875:58                          performLayout
../packages/flutter/src/rendering/layer.dart.js 3279:14                          [_layoutWithoutResize]
../packages/flutter/src/rendering/layer.dart.js 6876:107                         flushLayout
../packages/flutter_test/src/_matchers_web.dart.js 3990:30                       drawFrame
../packages/flutter/src/rendering/layer.dart.js 6128:12                          [_handlePersistentFrameCallback]
../packages/flutter/src/scheduler/binding.dart.js 764:9                          [_invokeFrameCallback]
../packages/flutter/src/scheduler/binding.dart.js 732:37                         handleDrawFrame
../packages/flutter_test/src/_matchers_web.dart.js 3954:12                       scheduleWarmUpFrame
../packages/flutter/src/widgets/widget_span.dart.js 52123:11                     <fn>
../packages/flutter/src/widgets/widget_span.dart.js 52125:7                      runApp
../packages/flutter_test/src/_matchers_web.dart.js 3647:18                       _runTestBody
../dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 84:54            runBody
../dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 123:5            _async
../packages/flutter_test/src/_matchers_web.dart.js 3644:20                       [_runTestBody]
../dart-sdk/lib/async/zone.dart 1386:13                                          _rootRunBinary
../dart-sdk/lib/async/zone.dart 1272:19                                          runBinary
../packages/flutter_test/src/_matchers_web.dart.js 3636:16                       [_runTest]
../packages/flutter_test/src/_matchers_web.dart.js 4072:44                       <fn>
../packages/fake_async/fake_async.dart.js 141:96                                 <fn>
../dart-sdk/lib/async/zone.dart 1354:13                                          _rootRun
../dart-sdk/lib/async/zone.dart 1258:19                                          run
../dart-sdk/lib/async/zone.dart 1788:67                                          _runZoned
../dart-sdk/lib/async/zone.dart 1711:10                                          runZoned
../packages/clock/src/stopwatch.dart.js 364:18                                   withClock
../packages/fake_async/fake_async.dart.js 141:55                                 <fn>
../dart-sdk/lib/async/zone.dart 1354:13                                          _rootRun
../dart-sdk/lib/async/zone.dart 1258:19                                          run
../dart-sdk/lib/async/zone.dart 1788:67                                          _runZoned
../dart-sdk/lib/async/zone.dart 1711:10                                          runZoned
../packages/fake_async/fake_async.dart.js 141:20                                 run
../packages/flutter_test/src/_matchers_web.dart.js 4067:17                       runTest
../packages/flutter_test/src/_matchers_web.dart.js 5312:24                       <fn>
../packages/test_api/src/frontend/async_matcher.dart.js 862:17                   <fn>
../dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 45:50            <fn>
../packages/stack_trace/src/stack_zone_specification.dart.js 179:98              <fn>
../packages/stack_trace/src/stack_zone_specification.dart.js 247:16              [_run]
../packages/stack_trace/src/stack_zone_specification.dart.js 179:80              <fn>
../dart-sdk/lib/async/zone.dart 1362:47                                          _rootRunUnary
../dart-sdk/lib/async/zone.dart 1265:19                                          runUnary
../dart-sdk/lib/async/future_impl.dart 155:18                                    handleValue
../dart-sdk/lib/async/future_impl.dart 707:44                                    handleValueCallback
../dart-sdk/lib/async/future_impl.dart 736:13                                    _propagateToListeners
../dart-sdk/lib/async/future_impl.dart 406:9                                     <fn>
../packages/stack_trace/src/stack_zone_specification.dart.js 247:16              [_run]
../packages/stack_trace/src/stack_zone_specification.dart.js 170:71              <fn>
../dart-sdk/lib/async/zone.dart 1354:13                                          _rootRun
../dart-sdk/lib/async/zone.dart 1258:19                                          run
../dart-sdk/lib/async/zone.dart 1162:7                                           runGuarded
../dart-sdk/lib/async/zone.dart 1202:23                                          callback
../dart-sdk/lib/async/schedule_microtask.dart 40:11                              _microtaskLoop
../dart-sdk/lib/async/schedule_microtask.dart 49:5                               _startMicrotaskLoop
../dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 166:15           <fn>

The following RenderObject was being processed when the exception was fired: RenderParagraph#e6e8f relayoutBoundary=up1 NEEDS-PAINT:
  creator: RichText ← Text ← Center ← Container-[#9a020] ← [root]
  parentData: offset=Offset(0.0, 0.0) (can use size)
  constraints: BoxConstraints(0.0<=w<=800.0, 0.0<=h<=600.0)
  size: Size(640.0, 40.0)
  textAlign: start
  textDirection: ltr
  softWrap: wrapping at box width
  overflow: clip
  maxLines: unlimited
This RenderObject had the following child:
    text: TextSpan
```

This reverts commit aa3bb5e3.

CppWinRT is a tool that generates standard C++17 header-file libraries
for Windows Runtime (WinRT) APIs. A more detailed introduction to
C++/WinRT can be found in the Microsoft documentation at
https://docs.microsoft.com/en-us/windows/uwp/cpp-and-winrt-apis/.

The source code is available under an MIT license, from
https://github.com/microsoft/cppwinrt.

Bug: https://github.com/flutter/flutter/issues/70205