TTP# 342872 - EDITOR: Regression: CRASH: FSourceControlModule::ShutdownModule
The SVN source control provider module was being shutdown before the main source control module, leading to a crash.
The source control module now watches for its active provider module being unloaded, and will gracefully reset itself to the default (dummy) provider if that happens.
I also added these same checks to the source code access module, as it uses the same provider modules mechanism.
#codereview Thomas.Sarkanen, Max.Preussner
[CL 2244286 by Jamie Dale in Main branch]
- Changed Core module to use Core.h (removed CorePrivate.h)
- CorePrivate.h only included Core.h, so their PCHs were identical other than name
- Does not affect modular builds, as we need different defines for DLLExport/DLLImport for private and public PCH headers
[CL 2221011 by Mike Fricker in Main branch]
