[llvm] [MsgPack] Use JSON schema boolean resolution rules (PR #170561)

[Carl Ritson via llvm-commits]

https://github.com/perlfu approved this pull request.

I agree this is a step in the right direction.
At a minimum, the increased test coverage this provides is much needed.

Please give it another day or so before merging, in case anyone else has time to review.

https://github.com/llvm/llvm-project/pull/170561