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>

Add some nullability tests for Generate Type and fix one bug

Closes https://github.com/dotnet/roslyn/issues/30316

Also add extension methods to help with nullability

Set focus to editor before finding text

Add a bunch of nullability support to some code generation helpers

* Fix for typing semicolon inside comments in an argument list

* Change to previously existing method

* Fix

Closes #36401

Merge release/dev16.2-preview3 to master

* Add optional [warnings | annotations] keyword to nullable directive

* pragma warning <setting> nullable -> nullable <setting> warnings

* Implement /nowarn:nullable

Fix stack overflow error in Complete Statement 

Fixes #36037

Apply a hang mitigating timeout to UI thread operations

Implement subset-based ordering for naming rules

Update naming styles to ensure .editorconfig is the code style "source of truth"

Change `??=` for nullable value types as specified in LDM

added basic completion statement telemetry

Remove duplication in AbstractSymbolCompletionProvider.CreateItems

* dotnet/master: (63 commits)
  Fix stack overflow in requesting syntax directives (#36347)
  crash on ClassifyUpdate for EventFields (#35962)
  Disable move type when the options service isn't present (#36334)
  Fix crash where type inference doing method inference needs to drop nullability
  Fix parsing bug in invalid using statements (#36428)
  Do not suggest or diagnose use compound assignment when right hand of binary operator is a throw expression
  Add option to emit nullable metadata for public members only (#36398)
  Added null checks on F# external access services (#36469)
  Deal with discovering extra .editorconfig files
  Re-enable MSBuildWorkspaceTests.TestEditorConfigDiscovery
  Add support to VisualStudioMSBuildInstalled to support minimum versions
  Fix configuration of accessibilities in editorconfig
  Shorten a resource ID
  Revert "Extract the RDT implementation for Misc files and VS open file tracker"
  Add nullability support to use local function
  Add EditorFeatures.WPF dependency to F# ExternalAccess
  Ensure NullableWalker.AsMemberOfType locates the right new container for the member. (#36406)
  Replace `dynamic` with `object` when substituting constraints. (#36379)
  Add some string descriptions
  Adjust type of out var based on parameter state (#36284)
  ...

Revert 35746

Move to a different lowering from for nullable value types to work around a bug in TransformCompoundAssignmentLHS. Addressed PR feedback.

Fixes #36346

Fix crash where type inference doing method inference needs to drop nullability

Fix #36060: Group Completion Providers using IsExclusive

We had two overloads of AbstractSymbolCompletionProvider.CreateItems,
once which handles the case of a single file and one that handles
linked files. The code is almost identical, but the linked file one
incorrectly handled the case of not having any symbols. Rather than
fixing the bug in just that branch, I'm refactoring it to simply
remove the second copy so both the single file and linked file cases
go through the same helper. The intent here is to avoid hiding simple
bugs that had nothing to do with linked files in the linked-file-only
path.

Fixes https://github.com/dotnet/roslyn/issues/36080 by virtue of
deleting the offending code entirely. No new tests are added since
I've confirmed that the existing tests (once the refactoring was
complete) would have been sufficient for discovering this problem.

Use MEF to provide implementation contract

I added a test to ensure the inferrer no longer crashes, but
https://github.com/dotnet/roslyn/issues/36046 still blocks the ability
for it to actually pass. The test is then added skipped until that
works.

This reverts commit ff0359d9.

Merge pull request #36494 from YairHalberstadt/use-compound-assignment-not-suggested-when-right-hand-is-throw-expression

Do not suggest or diagnose use compound assignment when right hand of…

Add nullability support to use local function