[clang] [clang][ThreadSafety] Enable late parse for all capabilities, under the experimental flag (PR #212615)

[Marco Elver via cfe-commits]

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

Generally LGTM. I hope some of the other reviewers will also find the time to take a look.

https://github.com/llvm/llvm-project/pull/212615