[analyzer] Support interestingness in ArrayBoundV2 (#78315)

This commit improves alpha.security.ArrayBoundV2 in two connected areas:
(1) It calls `markInteresting()` on the symbolic values that are
responsible for the out of bounds access.
(2) Its index-is-in-bounds assumptions are reported in note tags if they
provide information about the value of an interesting symbol.

This commit is limited to "display" changes: it introduces new
diagnostic pieces (potentially to bugs found by other checkers), but
ArrayBoundV2 will make the same assumptions and detect the same bugs
before and after this change.

As a minor unrelated change, this commit also updates/removes some very
old comments which became obsolete due to my previous changes.