LdrpInitializeProcessCompat: Allow the process to query manifest versions

Currently, there is one shared 'Compatibility' version, that includes both the version set using shims, and the version set from the .exe.manifest (supportedOS fields).

LdrpInitializeProcessCompat needs to be updated to not overwrite the field that can be read using RosGetProcessCompatVersion(), but to write to an additional field.

This way, the loader and our shims can both query the user- (or system-) applied shim version, as well as the version requested by the process itself (using the .exe.manifest)