Add versionremoved directive

[hugovk]

Feature or Bugfix

• Feature

Purpose

• Add versionremoved directive, for when removing features.
• Similar to existing versionadded, versionchanged, and deprecated.

Relates

• Fixes Add versionremoved directive to complement versionadded and deprecated #11480.

[CAM-Gerlach]

Not a maintainer here ofc, and personally I'm working on a suite of much more capable directives to replace the upstream builtin version* suite with CPython's deprecated-removed as a basis (which more or less already replaces this), but it seems eminently sensible and straightforward, IMO, to add a versionremoved to the base suite to parallel the others. A few minor comments.

[AA-Turner]

Thanks!

[CAM-Gerlach]

Thanks @AA-Turner !