There was a previous parsing change (#32999) which modified namespace
parsing to allow modifiers and attributes on namespaces, to improve
error recovery.

This PR contained a bug because it didn't move the incremental parsing
check to before parsing attributes and modifiers, which should now
be included in incremental parsing to prevent changes from being dropped

Fixes #37665, #37664, #37663

Skip tests requiring legacy EditorConfig

Update LanguageServices dependencies

Update version of ICSharpCode.Decompiler and M.CA.FlowAnalysis.Utilities

Fix #37456 in 16.2 by cherry-picking commit a0009846 (from PR #37487)

Move to release versions.

Workaround IExperimentationService having a UI thread dependency

Right now we are seeing deadlocks where MEF is trying to create
the RoslynVisualStudioWorkspace on a background thread, and that
deadlocks because the IExperimentationService it tries to use has a
UI thread dependency. This breaks that specific cycle by avoiding using
the IExperimentationService until on the UI thread -- we know we can't
be asked for document options until we have documents, and that can't
happen until we get projects. Thankfully, the creation of projects
are still UI affinitized so we can initialize it there.

Show nullability flow analysis in Quick Info

Revert "use the source instead of the name to find nuget packages"

This reverts commit 0d8d2afb.

Skip BasicEditAndContinue tests

If you mouse over a local, field, etc., and we have computed nullable
flow analysis for it, we'll tell you whether the compiler thinks the
item is null or not at that point.

- Microsoft.DotNet.Arcade.Sdk - 1.0.0-beta.19326.2

Related to #35619.

Fix GetHashCode on constructed types with annotated type arguments

Conflicts:
	src/Compilers/CSharp/Test/Semantic/Semantics/NullableReferenceTypesTests.cs

Handle lazy loading of analyzer command handlers

Add workarounds to IDE analyzers for missing IOperation/CFG support for using declarations

- Microsoft.DotNet.Arcade.Sdk - 1.0.0-beta.19324.24

Pass feature flags to the remote workspace

Nullable Analysis Pay-for-play

Fix typo in task namespace in docs

* Correctly report nullability of tuples in the semantic model:
- Store the original tuple literal rather than just its type
- Visit the original literal without diagnostics only in the nullability walker to understand its type
- Update the generator to allow force visiting fields in the nullable re-writer
- Update type checker to allow checking of converted types too
- Update various tuple tests to be correct
- Add extra tests

This implements IExperimentationService in the remote workspace; any
request for feature flags is forwarded to the main Visual Studio process
and the feature flag is queried there.
Co-authored-by: NJoey Robichaud <jorobich@microsoft.com>
Co-authored-by: NHeeJae Chang <hechang@microsoft.com>

Couple of AD0001 fixes for unused parameter analyzer

Unwrap nullability-wrapped symbols in object initializer completion 

Fixes #36304

Fixes #33464