[clang] [clang][driver] Support `--precompile` and `-fmodule-*` options in Clang-CL (PR #98761)

[Sharadh Rajaraman via cfe-commits]

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@@ -242,7 +242,7 @@ bool types::isCXX(ID Id) {
   case TY_CXXHUHeader:
   case TY_PP_CXXHeaderUnit:
   case TY_ObjCXXHeader: case TY_PP_ObjCXXHeader:
-  case TY_CXXModule: case TY_PP_CXXModule:
+  case TY_CXXModule: case TY_PP_CXXModule: case TY_ModuleFile:
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sharadhr wrote:

This is required to get rid of the `Wunused-argument: /std:c++20` warning.

I realised that the input file was `TY_ModuleFile` which led the Clang-CL driver to interpret it as a C file, and not a CXX file, and then eventually emitting this error. 

https://github.com/llvm/llvm-project/pull/98761