[clang] [clang][Driver] Support passing arbitrary args to `-cc1as` with `-Xclangas`. (PR #100714)

[Hubert Tong via cfe-commits]

hubert-reinterpretcast wrote:

@alexrp, the test added fails on AIX: https://lab.llvm.org/buildbot/#/builders/64/builds/3074
Clang on AIX does not use the integrated assembler for assembly files.

https://github.com/llvm/llvm-project/pull/100714