Asking for Location.SourceTree may not produce a syntax tree, even if there
is a backing syntax tree, because a speculative tree node may produce NoLocation
when asked for one, even if there is a backing tree. This change stops us from
trying to do the SyntaxTree->Location->SyntaxTree roundtrip because it's not guaranteed
to succeed.

Fixes #37454

Merge release/dev16.3-preview1 to master

Merge release/dev16.2 to release/dev16.3-preview1

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

Remove unneeded method

Move lsp code actions

* Don't drop a token passed to a syntax factory method.

* Delete unintended comment.
Fixes #37467

Support GetDeclaredSymbol on ForeachStatementSyntax and add tests for…

* 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

* Fix region tracking for regions with local functions

Fixes #37427

* Add to test pre review comment.

Update code style analyzer

Fixes #37467

Merge NullableAnnotation.NotApplicable and Disabled to None, and rename NullableFlowState.NotApplicable to None for consistency

Add initial GetDeclaredSymbol support for inferred VariableDeclaratorSyntax and SingleVariableDesignationSyntax nodes

Split liveshare handlers

Merge NullableAnnotation.NotApplicable and Disabled to None, and rename NullableFlowState.NotApplicable to None for consistency.

Use AnalyzerConfigOptionsProvider when available

Use the SnapshotManager to store the variable types as it was already doing this, and handle nested scopes correctly.

Add GetDeclaredSymbol support for nullability in variable declarations. Not handled are linq or foreach iteration variable declarations.