[clang] [Clang] Introduce FunctionParmPackDecl for expanded lambda captures (PR #107995)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

This seems reasonable to me, and the code itself is fine.  I wouldn't mind a few of the others getting a chance to make a comment on it, and for me myself to consider the implications of it.  So this just needs time to bake in my head.

https://github.com/llvm/llvm-project/pull/107995