[llvm] [LLVM][Clang][AArch64] Implement AArch64 build attributes (PR #118771)

[via llvm-commits]

sivan-shani wrote:

> This needs tests.
Will fix the comments and commit, then will commit tests.
> What about the assembly parser for the new directives?
Work divided to emitting/parsing. This change cover emitting Asm and ELF, will add parsers later. 

https://github.com/llvm/llvm-project/pull/118771