P2445R1 `forward_like()`

[StephanTLavavej]

P2445R1 forward_like()

Feature-test macro (expected):

#define __cpp_lib_forward_like 202207L

[CaseyCarter]

We now have both a core and library feature for explicit object member functions, and they're still not usable for deduplication because of the conversion-to-private-base issue. 😿