[CIR][ABI][NFC] Add x86_64 ABI parity tests (#191259)
Add three test files for CIR ABI parity on x86_64, all with
CIR/LLVM/OGCG checks:
- uncopyable-args.cpp — 24 functions covering non-copyable and
move-only types (trivial, default-ctor, move-ctor, etc.)
- x86_64-arguments.cpp — 26 functions covering C++ struct passing,
inheritance, member pointers, empty bases, packed structs
- attr-noundef.cpp — 26 functions covering noundef placement on
structs, unions, vectors, member pointers, _BitInt
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