P2786R13 Trivial Relocatability

[StephanTLavavej]

WG21-P2786R13 Trivial Relocatability

This is a Core paper with Library impact.

Feature-test macro:

#define __cpp_lib_trivially_relocatable 202502L

Note: We're focused on implementing the remaining library-only features in C++23. Until that's done, we will NOT be accepting PRs for C++26 features.