[AArch64][PAC][clang][ELF] Support PAuth ABI core info (#85235)

Depends on #87545

Emit PAuth ABI compatibility tag values as llvm module flags:
- `aarch64-elf-pauthabi-platform`
- `aarch64-elf-pauthabi-version`

For platform 0x10000002 (llvm_linux), the version value bits correspond
to the following LangOptions defined in #85232:

- bit 0: `PointerAuthIntrinsics`;
- bit 1: `PointerAuthCalls`;
- bit 2: `PointerAuthReturns`;
- bit 3: `PointerAuthAuthTraps`;
- bit 4: `PointerAuthVTPtrAddressDiscrimination`;
- bit 5: `PointerAuthVTPtrTypeDiscrimination`;
- bit 6: `PointerAuthInitFini`.

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Co-authored-by: Ahmed Bougacha <ahmed@bougacha.org>