Draft: cxxmodules: Enable support for clang-cl

This MR enables support for clang-cl based on changes merged in LLVM 19.1.0-rc3 and later. The LLVM PRs that enable this are as follows:

• [clang][driver] Support -x for all languages in CL mode #89772
• [clang][driver][clang-cl] Support --precompile and -fmodule-* options in Clang-CL #98761
• [clang][driver][clang-cl] Fix unused argument warning for /std:c++20 for precompiled module inputs to clang-cl #99300.

Fixes: #25731 (closed)