[clang] [llvm] [NFC][analyzer] Extract bounds checking library (PR #202372)

[Donát Nagy via cfe-commits]

NagyDonat wrote:

@Xazax-hun As a general reply to several of your suggestions: this commit moves code between source files, so I would like to avoid modifications (especially renaming things) unless they are absolutely necessary. If we move and rename a function, its history is essentially lost, future readers would need to review this (big!) PR to notice that its logic previously it existed under a different name in a different location.

I understand that you are not satisfied with lots of names, but I think it is important to postpone renaming them into a separate PR. (In fact, perhaps I should temporarily revert some renamings.)

https://github.com/llvm/llvm-project/pull/202372