Merge branch 'tk/untracked-cache-with-uall'

The performance of the "untracked cache" feature has been improved
when "--untracked-files=<mode>" and "status.showUntrackedFiles"
are combined.

* tk/untracked-cache-with-uall:
  untracked-cache: support '--untracked-files=all' if configured
  untracked-cache: test untracked-cache-bypassing behavior with -uall