* 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

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

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

Update src/Features/CSharp/Portable/UseExpressionBodyForLambda/UseExpressionBodyForLambdaCodeRefactoringProvider.cs

* 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

Address PR feedback and add an internal abstract property `SyntaxEditorBasedCodeFixProvider.CodeFixCategory` to determine the category of code fixes offered by our code fixers.

Fixes #29819

* 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