reland [InlineAsm] wrap ConstraintCode in enum class NFC (#66264)

reland [InlineAsm] wrap ConstraintCode in enum class NFC (#66003)

This reverts commit ee643b70.

Fix up build failures in targets I missed in #66003

Kept as 3 commits for reviewers to see better what's changed. Will
squash when
merging.

- reland [InlineAsm] wrap ConstraintCode in enum class NFC (#66003)
- fix all the targets I missed in #66003
- fix off by one found by llvm/test/CodeGen/SystemZ/inline-asm-addr.ll