[Docs][Clang] Missing DR status for C++23-era papers in cxx_status.html (#68846)
List the following C++23-era WG21 papers as Defect Reports in
cxx_status.html as per WG21 meeting minutes.
- [P1949R7](https://wg21.link/p1949r7) (C++ Identifier Syntax using
Unicode Standard Annex 31)
- [P2156R1](https://wg21.link/p2156r1) (Allow Duplicate Attributes)
- [P2036R3](https://wg21.link/p2036r3) (Change scope of lambda
_trailing-return-type_)
- [P2468R2](https://wg21.link/p2468r2) (The Equality Operator You Are
Looking For)
- [P2327R1](https://wg21.link/p2327r1) (De-deprecating `volatile`
compound operations)
- [P2493R0](https://wg21.link/p2493r0) (Missing feature test macros for
C++20 core papers)
- [P2513R3](https://wg21.link/p2513r3) (`char8_t` Compatibility and
Portability Fix)
- [P2460R2](https://wg21.link/p2460r2) (Relax requirements on `wchar_t`
to match existing practices)
- [P2579R0](https://wg21.link/p2579r0) (Mitigation strategies for
[P2036](https://wg21.link/p2036) ”Changing scope for lambda
_trailing-return-type_”)