[clang] [analyzer] Modernize, improve and promote chroot checker (PR #117791)

[Balazs Benics via cfe-commits]

https://github.com/steakhal requested changes to this pull request.

This checker deserved some love for sure. Thank you for pushing for this.
I left quite a few comments, touching style and also direction of this patch.
Thanks Vince!

https://github.com/llvm/llvm-project/pull/117791