P3168R2: Give `std::optional` Range Support

[ldionne]

Link: https://wg21.link/P3168R2

[elhewaty]

Hi @ldionne, I am interested in working with you on implementing the new c++26 features. I found a lot of related issues. Please guide me through the issues. can we start with easy ones and then harder ones? I am passionate about compilers and clang.

Thanks