[clang] [nfc][analyzer] Add MemSpace trait to program state (PR #123003)

[Balazs Benics via cfe-commits]

steakhal wrote:

I've pushed a couple of commits to sync this PR with what I had in mind.
I hope you don't mind @Flandini.

Please anyone do a thorough review.

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I've considered uplifiting a couple of the `VarRegion::getStackFrame()`, and similar `getStackFrame()` functions, because internally they would use the memory space to resolve to the stack frame. I still consider it, but it would need a similar migration: introduce a new overload that takes the State, and try to eradicate the overload that doesn't take any State. Then keep the cases that cannot be uplifted. I found this tedious, and not strictly necessary as a first step to merge this PR. It would also "pollute" the API surface with the leftover APIs, which isn't ideal.

https://github.com/llvm/llvm-project/pull/123003