[clang] [Modules] Add -cc1 -flate-module-map-file to load module maps after PCMs (PR #88893)

[Ian Anderson via cfe-commits]

ian-twilightcoder wrote:

+ @Bigcheese and @jansvoboda11 as I think they know this area of the code better

https://github.com/llvm/llvm-project/pull/88893