[clang] [clang][analyzer] Add taintedness to argv (PR #178054)

[Donát Nagy via cfe-commits]

https://github.com/NagyDonat approved this pull request.

Overall looks good to me, I'm happy to see this improvement :smile:

I think the change is ready to use and would work correctly; but I added a few stylistic remarks about messaging, comments and testing.

https://github.com/llvm/llvm-project/pull/178054