[clang] [clang][Analysis] Add argument accessors to clang::AnyCall (PR #212934)

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iitianpushkar wrote:

> I think this looks solid, thanks!
> 
> If it is not too much work to add a test it would be great! Otherwise, if it starts to get out of hand, I think it might be fine to say that this will be used and tested indirectly in a follow-up PR.

Thanks! 
I don't think it will take much work to add a test for this one. I will update the patch with a test and improved comment.

https://github.com/llvm/llvm-project/pull/212934