EnC: Tweak handling of out-of-sync documents to work around source file content inconsistencies (#40947)

* Do not block in presence of out-of-sync documents.

Instead, ignore any changes made to these documents while debugging until their content matches the source used to build the baseline DLL.

* Only check output PDB, not debugger SymReader, for document checksums.
Turns out SymReader does not support reading document checksums once EnC changes have been applied.

Better handle errors that might occur when validating checksums. Previously some of the errors were not reported as diagnostics.

We previously blocked EnC when we observed a source file that is out-of-sync (i.e. its current content does not match the checksum in the originally built PDB). We can however just ignore these files and report a warning that changes made to this file won’t be applied until the file content is reverted back to the state it was when the PDB was built (the file transitions to “matching” state). Once a file is in matching state it can’t change back to another state. We know that we have not applied any change to the code that was compiled from the file because we ignored the file while it was in out-of-sync state. Therefore we know that any changes made from now on can be safely applied to the debuggee.

If we can’t determine whether a file matches or not due to error reading the PDB or the source file content we can treat it similarly to out-of-sync file. That is, ignore any changes until we are able to confirm the file matches. That can happen if, e.g. the PDB is temporarily locked by another process and unlocked later.

Simplify implementation of GetStatusAsync.

Fixes VSO [1051496](https://dev.azure.com/devdiv/DevDiv/_workitems/edit/1051496) ([VS feedback](https://developercommunity.visualstudio.com/content/problem/880533/edits-were-made-which-cannot-be-compiled-stop-debu.html))

* Implement lambda discard parameters

* Remove duplicate tests

* Factor logic to recognize underscore tokens

* Align symbol display with other discards

* Distinguish discards in QuickInfo

* Add IsDiscard property instead of IDiscardSymbol

* Adjust IDE logic to use IsDiscard

* Avoid large tuple return

* Add test for ref/out discard parameters

* Address PR feedback and test plan ideas

* Allow in expression trees

* Support general discard parameters

* Add IDE tests

* Emit with unspeakable name

* Remove unused error code

* Only support lambdas

* Fix tests

* Address some PR feedback

* Address remaining feedback

* Address more feedback

* Fix conflict

* Update PublicAPI.Unshipped.txt

* Update PublicAPI.Unshipped.txt

* Add ChangeSignature tests

* Add SymbolCompletion tests

* Add InlineRename test

* Typo

* Remove BaseSolution property

* Refactor GetAllAddedSymbolsAsync

* Track documents that do not match the debuggee

* Handle design-time-only documents and documents with no sequence points

This reverts commit fc63c345.

* Report rude edits when updating method containing switch expression.

Fix stackalloc rude edits.

* Updating modifiers of local functions

* await foreach, await using

* Improve error message

* Distinguish async foreach/using from synchronous in error messages

* Using declaration

* Report rude edit when editing using statement/declaration around non-leaf AS

* Rude edits for switch with patterns

* Fix VB issues with active statements in nested single-line functions and when updating iterators

* Update comment

* Fix duplicate rude edit

If it's written to a warning annotation is displayed in the refactoring window to warn that semantics may change.

* Emit tests

* Report rude edits for unsupported DIM operations

* Allow EnC tests to specify TFMs to build against

* EnC: test against netcoreapp30

* Test fixes

* Fix merge

* Top-level types enumeration refactoring

* Simplify DefinitionMap

* Include namespaces in synthesized definition map

* Add SynthesizedNamespaceSymbol

* Embedded Attributes

* Test synthesized attributes

* Clean up EnC tests

* Clean up symbol matcher tests

* Ref readonly return type, in parameter symbol matching tests

* Enable using ref readonly returns, in parameters, ref structs during debugging

* More tests

* ReadOnly struct members

* Fix langauge version mismatch

* Merge fix ups

* Feedback, skip tests

The resource in question has an ID that is 414 characters long. This is
apparently too long for some of the tools used by the loc team, blocking
parts of their processes. The exact failure mechanism is not well
understood but in order to avoid problems with the final loc pass for
16.2 I'm just going to go ahead and shorten it.

Unfortunately no one knows how long resource IDs can be before they
cause problems. At the suggestion of the loc team I'm shortening this
one by 50 characters which lines up nicely with a natural break in the ID.

We support configuration for boolean and enum based code style option values. The only unsupported current code style option from this fixer is specification of modifiers order, which is a custom user supplied string.

(DisposableFieldsShouldBeDisposed)

We will now flag disposable creations in methods that do not escape the
method body (return value, out/ref params, assign to field/property, add
to collection, etc.). Additionally, we also flag disposable fields of
disposable types that are not disposed in the type's Dispose method.
Ported analyzers share the core dataflow analysis computation with the
analyzers in the roslyn-analyzers repo
(Microsoft.CodeAnalysis.FlowAnalysis.Utilities). This PR does not add
any code fixes. We already have a code
refactoring that offers wrapping a disposable creation within a using
statement. I am hoping to extend that to handle more cases and also
possibly convert it to a code fix in follow-up PR(s).

Add Configure severity code action to enable configuring severity of diagnostics using .editorconfig files (analyzer config documents)