[Bug c++/98940] Implement C++23 language features

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98940
Bug 98940 depends on bug 107684, which changed state.

Bug 107684 Summary: [C++23] P2589 - static operator[]
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107684

           What    |Removed                     |Added
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             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED