[BOLT] Map branch source address to the containing basic block in BAT YAML

Fix an issue where the profile for all branches that have a BRANCHENTRY
is dropped. If the branch has an entry in BAT, it will be translated to
its input offset. We used to only permit the basic block offset as a
branch source. Perform a lookup of containing basic block instead.

Test Plan: Updated bolt-address-translation-yaml.test

Reviewers: maksfb, dcci, rafaelauler, ayermolo

Reviewed By: maksfb

Pull Request: https://github.com/llvm/llvm-project/pull/91273