Merge branch 'ps/reflog-list' into HEAD

"git reflog" learned a "list" subcommand that enumerates known reflogs.

* ps/reflog-list:
  builtin/reflog: introduce subcommand to list reflogs
  refs: stop resolving ref corresponding to reflogs
  refs: drop unused params from the reflog iterator callback
  refs: always treat iterators as ordered
  refs/files: sort merged worktree and common reflogs
  refs/files: sort reflogs returned by the reflog iterator
  dir-iterator: support iteration in sorted order
  dir-iterator: pass name to `prepare_next_entry_data()` directly

diff --cc builtin/reflog.c
Simple merge

diff --cc t/t0600-reffiles-backend.sh
Simple merge

diff --cc t/t1405-main-ref-store.sh
Simple merge