Merge branch 'ps/refs-wo-the-repository'

Merge branch 'ps/refs-wo-the-repository'

The ref subsystem and the worktree API have been refactored to pass a
repository pointer down the call chain, allowing them to drop
references to the global 'the_repository' variable.  As part of this,
the handling of the 'core.packedRefsTimeout' configuration has been
moved into the per-repository ref store structure.

* ps/refs-wo-the-repository:
  refs: remove remaining uses of `the_repository`
  worktree: pass repository to public functions
  worktree: pass repository to file-local functions
  worktree: refactor code to use available repositories
  refs/files: drop `USE_THE_REPOSITORY_VARIABLE`
  refs/packed: de-globalize handling of "core.packedRefsTimeout"