[clang][Modules] Diagnose mismatching pcm dependencies in explicit buiilds (#137068)

In an explicit build, the dependency scanner generates invocations with
dependencies to module files to use during compilation. The pcm's passed
in the invocations should match the ones that were imported by other
modules that share the same dependencies.

We have seen bugs caused from incorrect invocations that mismatch which
module file to load. When this happens report it as a warning, to help
with investigations, as that should never occur in a well behaved build
scheduled from the dependency scanner.

The warning flag is off by default.

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