Bug: https://github.com/flutter/flutter/issues/77624

This updates Flutter.*Codec `decode:` implementations to treat empty
messages as equivalent to nil or NSNull, which avoids a crash when we
subsequently otherwise try to read the type/value from the message. This
handles the case where the sender were to send `null` over the channel.
e.g.,

    final channel = BasicMessageChannel<Object?>('somechannel', StandardMessageCodec());
    channel.send(null);

It also updates the macOS embedder to send nil to the decoder when a
zero-length message is received in order to be consistent with the iOS
embedding.

Previously, the macOS embedder always encoded platform messages as
NSData regardless of length:
https://github.com/flutter/engine/blob/ba93431e6885f94614d91c291ae0336bac6b70b0/shell/platform/darwin/macos/framework/Source/FlutterEngine.mm#L498-L500

The iOS embedder did not have this issue since it special-cased
zero-length messages as nil:
https://github.com/flutter/engine/blob/ba93431e6885f94614d91c291ae0336bac6b70b0/shell/platform/darwin/ios/framework/Source/platform_message_router.mm#L23-L26

Bug: https://github.com/flutter/flutter/issues/78003

* Test docker image update.

Do not review.

* Test build in a VM.

* Add project name.

* Update image type.

* Add apt-get dependencies.

* Update dependencies.

* Update gcloud packages installation.

* Update dockerfile.

* Fix errors in dockerfile.

* Fix dockerfile.

* Organize docker file to make it more readable.

Bug:78453
Co-authored-by: Nyusufm <mohsinally@google.com>

* Modifications to gtest_util.h to build in Flutter

* Modifications to Range to build in Flutter

* Modifications to UiaRegistrarWin to build in Flutter

* Modifications to EnumVariant to build in Flutter

* Modifications to AXActivePopup to build in Flutter

* Modifications to ScopedBstr to build in Flutter

* Modifications to atl.h/atl_module.h to build in Flutter

* Modifications to ScopedVariant to build in Flutter

* Modifications to VariantUtil to build in Flutter

* Modifications to ScopedSafearray to build in Flutter

* Modifications to VariantVector to build in Flutter

* Add BASE_UNLIKELY, BASE_LIKELY and BASE_FALLTHROUGH macros to compiler_specific.h

* Update BUILD files for Windows base/ and gfx/ unittests
Co-authored-by: NChris Bracken <chris@bracken.jp>

* fix numeric dependencies

* fix

* fix format

* Add the following APIs to StringUtils:

- NumberToString16
- JoinString
- ReplaceChars
- WideToUTF16
- UTF16ToWide

Implement the following APIs for Windows:

- UTF8ToUTF16
- UTF16ToUTF8

* Review comments

Add a couple TODOs for decimal formatting and use std::u16string::npos
rather than std::string::npos.

* Update licences_flutter
Co-authored-by: NChris Bracken <chris@bracken.jp>

Co-authored-by: NChris Bracken <chris@bracken.jp>