[clang] [Clang][P1061] Consolidate ResolvedUnpexandedPackExpr into FunctionParmPackExpr (PR #125394)

[Jason Rice via cfe-commits]

ricejasonf wrote:

@cor3ntin Sorry, I tried "Commit suggestion", but it didn't look like you can cast like that so I just reverted.

https://github.com/llvm/llvm-project/pull/125394