This is now annotated as non-null, so the check is pointless.

These are all functions are supposed to work equally well with
regular documents, additional documents, and analyzer config documents.
However, they were all calling GetDocument that would only work with
the first kind.

The annotation is for the most part straightforwad. This removes a hack
where rather than passing some things through the VisualStudioProject
constructor, we just assigned some properties after creation. This
is now cleaned up since it made annotation problematic.

Move internal option SimplificationOptions.NamingPreferences into a separate internal type NamingStyleOptions and move few more functionality into shared layer

* Remove IsCompilerDiagnostic, IsCompilerDiagnosticAnalyzer from DiagnosticAnalyzerInfoCache

* Separate DiagnosticAnalyzer descriptor cache from host analyzers

* Split and rename file

This wasn't necessarily safe -- if we did get a null for
HostDiagnosticUpdateSource, then any analyzers that had to report
loading issues would have thrown NullReferenceExceptions. This replaces
the use with an existing mock.

Follow up to https://github.com/dotnet/roslyn/pull/42015/files#r385741503
This change allows couple of things:
1. Make C# and VB ISyntaxFactsService implementation private nested types.
2. Aid future porting of analyzers to CodeStyle layer by moving bunch of our analyzers/fixers/helpers to use ISyntaxFacts as opposed to ISyntaxFactsService, latter is not available in CodeStyle analyzer layer.

Closes #41260

Split ISyntaxFactsService into two parts:

1. `ISyntaxFacts`: Pure data interface to query about syntactic facts. This is moved to CompilerExtensions shared project and can be used by analyzers.

2. `ISyntaxFactsService`: Derives from ISyntaxFacts and ILanguageService and is present in the WorkspaceExtensions shared project. This enables Code fixes and Workspaces layer to access the same functionality via a language service, i.e. `GetLanguageService<ISyntaxFactsService>`.

Note that we cannot use a partial declaration for `ISyntaxFactsService` instead of `ISyntaxFacts`. This causes `ISyntaxFacts` to be defined in both the CodeStyle analyzer and CodeStyle fixer assembly (former imports CompilerExtensions and latter imports WorkspaceExtensions), which leads to type conflicts. We also cannot follow the approach taken for `ISyntaxKindsSevice` as it defines the second partial declaration `ISyntaxKindsSevice` which sub-types `ILanguageService` in Workspaces project, leading to the language service not being defined in CodeStyle fixer assembly, which will cause any code fix requesting `GetLanguageService<ISyntaxKindsService>` to fail. The only feasible approach for us to have the functionality available in shared analyzer layer is to split out the pure data query part of the service to a separate type, as done in this PR. I will send a follow-up PR to also split `ISyntaxKindsService` similarly. Hoepfully, these two are the only language services that are commonly used by our analyzers, and we will not require any more such splits.

* ProjectInfo argument validation

* Clean up usage of ToImmutableReadOnlyListOrEmpty

* Reorder With- methods

* Clean up DocumentInfo and SolutionInfo

* Renames

* Correct nullability

* Add more tests

* Fix generator NRE

* Rmeove unnecessary checks, dead code

* Add more list tests, share test helpers

This reverts commit 646489a3.