[clang] [LifetimeSafety] Support allocating/freeing functions annotated `ownership_takes`/`ownership_returns` (PR #213439)

[Gábor Horváth via cfe-commits]

https://github.com/Xazax-hun approved this pull request.

I wonder what happens if a user-defined delete operator is annotated with these. Might be worth having some tests just to make sure the diagnostics make sense and we do not crash.

Overall, looks good to me, some nits inline. 

https://github.com/llvm/llvm-project/pull/213439