Merge branch 'bl/cherry-pick-empty'

Allow git-cherry-pick(1) to automatically drop redundant commits via a new `--empty` option, similar to the `--empty` options for git-rebase(1) and git-am(1). Includes a soft deprecation of `--keep-redundant-commits` as well as some related docs changes and sequencer code cleanup. * bl/cherry-pick-empty: cherry-pick: add `--empty` for more robust redundant commit handling cherry-pick: enforce `--keep-redundant-commits` incompatibility sequencer: do not require `allow_empty` for redundant commit options sequencer: handle unborn branch with `--allow-empty` rebase: update `--empty=ask` to `--empty=stop` docs: clean up `--empty` formatting in git-rebase(1) and git-am(1) docs: address inaccurate `--empty` default with `--exec`