CheckContainsProject asserts the project exists, no need to duplicate
it.

The implementation in SolutionState.RemoveDocumentsFromMultipleProjects
is heavily inspired (i.e. copy/pasted and tweaked appropriately) from
AddDocumentsToMultipleProjects.

This base type doesn't really make things "simpler" if the uses still
have static readonly lambdas. It may reduce things by a few lines of
code but that's not really simpler.

* CodeStyle+Workspaces -> CompilerExtensions
* CodeStyle+Features -> Analyzers
* CodeStyleFixes+Workspaces -> WorkspaceExtensions
* CodeStyleFixes+Features -> CodeFixes

Extracted from #41363
Third follow-up item from #41462

Apart from adding resx files, changes also include:
1. Moving resource strings duplicated across Workspaces and CodeStyle layer into the shared resx files
2. Source file changes to use the resource strings from the shared resx.

We should no longer require use of `#if CODE_STYLE` in the shared layer for the purpose of resource strings.

* Clean up string resources, use Arcade resx generator

* CodeLens resources


* Use NET20 instead of NETFX20

Part of https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1065328

We suppressed these because we were on the .NET Portable profile and
thus couldn't do the anything else. We're no longer on the portable
profile.

* AssetProvider refactoring

* Remove usage of SessionWithSolution

* Move Razor specific service base