P2637R3: Member `visit`

[ldionne]

Link: https://wg21.link/P2637R3

BEGIN-RST-NOTES
Change of ``__cpp_lib_variant`` is completed in LLVM 20. Change of ``__cpp_lib_format`` is blocked by `P2419R2 <https://wg21.link/P2419R2>`__.
END-RST-NOTES

[ldionne]

This issue has already been implemented and was created for tracking purposes only.

[Zingam]

Fixed #79032 #76447