Add storage of UNIX file mode metadata from diffs.
Review Request #12067 — Created Feb. 20, 2022 and submitted
FileDiffnow contain storage of old and new UNIX
file modes, which may be provided by the diff parser. These are
ultimately stored in
Right now, nothing consumes these within Review Board, but clients will
be able to make use of these to reflect file modes. In time, the plan is
to show these in the diff viewer.
All unit tests pass.