[clang] Show error if defaulted comparions operator function is volatile or has ref-qualifier &&.

This patch implemed the change proposed in [P2002R1] to 11.11.1 [class.compare.default] paragraph 1.

A defaulted compariosn operator function must be non-volatile and must either have no ref-qualifier or the ref-qualifier &.

Differential Revision: https://reviews.llvm.org/D148924