[clang] Implement P2266 Simpler implicit move

This Implements [[http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2266r1.html|P2266

 Simpler implicit move]].

Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>

Reviewed By: Quuxplusone

Differential Revision: https://reviews.llvm.org/D99005