Merge branch 'ab/reflog-prep'

Code refactoring in the reflog part of refs API.

* ab/reflog-prep:
  reflog + refs-backend: move "verbose" out of the backend
  refs files-backend: assume cb->newlog if !EXPIRE_REFLOGS_DRY_RUN
  reflog: reduce scope of "struct rev_info"
  reflog expire: don't use lookup_commit_reference_gently()
  reflog expire: refactor & use "tip_commit" only for UE_NORMAL
  reflog expire: use "switch" over enum values
  reflog: change one->many worktree->refnames to use a string_list
  reflog expire: narrow scope of "cb" in cmd_reflog_expire()
  reflog delete: narrow scope of "cmd" passed to count_reflog_ent()

Author: gitster