Our internal repo uses dotnet/roslyn as a submodule.  It has additional project.json entries that need to go through the same verification as dotnet/roslyn.  This updates RepoUtil so it can handle this structure.  In particular having the configuration file and generation files be in non-standard locations.

Account for bad commit missing

Make the GoToDefinitionHelper sit on top of the new FindUsages presenter

Move helpers to common layer.

Expose array sizes/lower bounds and type arguments custom modifiers in public API.

Allow clients to specify the behavior they want on hidden locations.

Add extension to test if a document is generated or not.

Add required reference to project.

Remove the synchronous GoToImplementation path for C#/VB.

Navigate to a span, not a position.

Infer better types for methods/variables with names we can understand.

Fixes #15315

Find-refs should open documents in a provisional tab.

Merge all the syntax indices into one index.

	Extract context object out so it can be used by other features.

Move to a streaming model for GoToImplementation (similar to how FindRefs works).