Merge branch 'ds/rebase-update-ref'

Merge branch 'ds/rebase-update-ref'

"git rebase -i" learns to update branches whose tip appear in the
rebased range with "--update-refs" option.
source: <pull.1247.v5.git.1658255624.gitgitgadget@gmail.com>

* ds/rebase-update-ref:
  sequencer: notify user of --update-refs activity
  sequencer: ignore HEAD ref under --update-refs
  rebase: add rebase.updateRefs config option
  sequencer: rewrite update-refs as user edits todo list
  rebase: update refs from 'update-ref' commands
  rebase: add --update-refs option
  sequencer: add update-ref command
  sequencer: define array with enum values
  rebase-interactive: update 'merge' description
  branch: consider refs under 'update-refs'
  t2407: test branches currently using apply backend
  t2407: test bisect and rebase as black-boxes