Fold mscorrc.dll into coreclr.dll

[huoyaoyuan]

Simplifies resource loading and get rid of module loading.

[jkotas]

LGTM otherwise. Thanks!

@janvorli Any concerns about this cleanup?

[janvorli]

@jkotas I don't have any concerns w.r.t. this change.

[jkotas]

I have done a pass over all remaining mscorrc occurrences. There are a few that can use cleanup:
src\libraries\System.Private.CoreLib\src\System\TypeLoadException.cs(74):// and ResourceId (mscorrc.dll). This allows customization of the -> rename to just mscorrc?
src\tests\Common\CLRTest.Execute.Batch.targets(301):copy %CORE_ROOT%\mscorrc.dll %LinkBin% > nul 2> nul -> delete

[jkotas]

Thanks!