as possible in PreferFrameworkTypeCodeFixProvider

Mainly more strong typing, removing type checks which were rendered
unnecessary because of strong typing.

before generating a code action id.

Remove subtypes that are no longer needed because we have syntax
generator API to generate the syntax in language agnostic manner.

Changelog:
Analyzer code: better naming
Test code: indentation and replace method with getter only autoprops.

predefined type keyword to framework type.

and plumb them through the UI, persistence, analyzer/fixer and
other parts of the system. update the simplifier to use the new options.
update codegen features as necessary.

This enables us to get better definite assignment behavior for
struct types imported from metadata that have only private fields,
and it also enables other useful diagnostics that we don't normally give
due to compatibility issues.
Closes #13203
Closes #13223

code path where code fix uses didn't check cancellation itself but just pass it down to workspace/compiler. but that will make it to not cancel if all diagnostics are already calculated and cached. so it will always run to end and then right after that, code fix service will throw cancellation exception.

by adding some cancellation here, we can prevent us from doing unnecessary work.

The ImportGroup element is just noise.  It was also used very inconsistently in the repo and often within the same project file.  Just remove it.

Members after dot are now provided by SymbolCompletionProvider. Fixes

Unwrap arrays when determining whether to show the builder for lambda
expressions.

this service will update solution checksum incrementally whenever workspace is changed.