Bring back type annotation support of dunder methods in stub generator (fix #12717)#12828

JelleZijlstra merged 2 commits intopython:masterpython/mypy:masterfrom

bluenote10:bugfix/selective_handling_of_dunder_methods_in_stubgenbluenote10/mypy:bugfix/selective_handling_of_dunder_methods_in_stubgenCopy head branch name to clipboard