[clang] [Clang][SemaCXX] Fix bug where unexpanded lambda captures where assumed to have size 1 (PR #101385)

[Younan Zhang via cfe-commits]

zyn0217 wrote:

Sorry I was wrong. I mixed up my patch along with this fix so I reapplied it to a clean branch locally, and this could also *fix* the above case. With this patch, we don't need to bother to handling PackExpansionExpr in the transform pass of PackIndexingExpr, which is great!

https://github.com/llvm/llvm-project/pull/101385