The "--format=<placeholder>" option of for-each-ref, branch and tag
learned to show a few more traits of objects that can be learned by
the object_info API.

* ot/ref-filter-object-info:
  ref-filter: give uintmax_t to format with %PRIuMAX
  ref-filter: add docs for new options
  ref-filter: add tests for deltabase
  ref-filter: add deltabase option
  ref-filter: add tests for objectsize:disk
  ref-filter: add check for negative file size
  ref-filter: add objectsize:disk option