[clang] [NFC][analyzer] Extract general logic in security.ArrayBound (PR #210774)

[Donát Nagy via cfe-commits]

NagyDonat wrote:

I started a CI job to also validate the NFCness of this PR on our set of open source projects.

Also I would wait a few days to give a chance for @Xazax-hun to review this, because he voiced strong opinions on the review of the ancestor PR (https://github.com/llvm/llvm-project/pull/202372).

https://github.com/llvm/llvm-project/pull/210774