ranges::shift_left
Implement the `ranges::shift_left` algorithm from [P2440R1](https://wg21.link/P2440R1). Closes: #134061 --------- Co-authored-by: Hui Xie <hui.xie1990@gmail.com> Co-authored-by: Louis Dionne <ldionne.2@gmail.com>
I believe this is a complete implementation of std::shift_left and std::shift_right from http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0769r2.pdf Some test cases copied-with-modification from D60027. Differential Revision: https://reviews.llvm.org/D93819