[clang] Add ElaboratedType sugaring for types on implicit special members
Extend the change from commit
15f3cd6bfc67 ([clang] Implement
ElaboratedType sugaring for types written bare, 2021-10-11, D112374)
to cover types in the signatures of implicit copy-constructor,
copy-assignment, move-constructor, and move-assignment members in
C++ record types.
With this fix, diagnostic messages print types of special members
consistently whether they are explicitly or implicitly defined.
Fixes: https://github.com/llvm/llvm-project/issues/59557
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D141441