Merge branch 'ps/read-object-info-improvements' into jch

Merge branch 'ps/read-object-info-improvements' into jch

The object-info API has been cleaned up.

* ps/read-object-info-improvements:
  packfile: drop repository parameter from `packed_object_info()`
  packfile: skip unpacking object header for disk size requests
  packfile: disentangle return value of `packed_object_info()`
  packfile: always populate pack-specific info when reading object info
  packfile: extend `is_delta` field to allow for "unknown" state
  packfile: always declare object info to be OI_PACKED
  object-file: always set OI_LOOSE when reading object info