community/py3-pip: make it easier to use as a pip517 builder
- community/py3-pip: remove deps on bundled dependencies
- community/py3-pip: disable check
- community/py3-pip: create fish completion
- community/py3-pip: update comment on certifi handling
- community/py3-pip: use default shell functions
- main/fish: don't ship pip{,3} completion, done in py3-pip