packfile: refactor `get_packed_git_mru()` to work on packfile store
The `get_packed_git_mru()` function prepares the packfile store and then
returns its packfiles in most-recently-used order. Refactor it to accept
a packfile store instead of a repository to clarify its scope.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
authored by