[3.13] gh-119336: Restore removed _PyLong_NumBits() function (GH-119418) (#119970)

gh-119336: Restore removed _PyLong_NumBits() function (GH-119418)

It is used by the pywin32 project.
(cherry picked from commit e50fac96e82d857ecc024b4cd4e012493b077064)

Co-authored-by: Ethan Smith <ethan@ethanhs.me>
3 files changed