Merge branch 'ps/reftable-detach' into ps/reftable-iterator-reuse

* ps/reftable-detach: reftable/system: provide thin wrapper for lockfile subsystem reftable/stack: drop only use of `get_locked_file_path()` reftable/system: provide thin wrapper for tempfile subsystem reftable/stack: stop using `fsync_component()` directly reftable/system: stop depending on "hash.h" reftable: explicitly handle hash format IDs reftable/system: move "dir.h" to its only user