R1:47a184e2a543

Display saved lint messages in Diffusion browse file

Test Plan:
Looked at https://secure.phabricator.com/diffusion/ARC/browse/master/src/difference/ArcanistDiffUtils.php.
Saw "Show 16 Lint Messages".
Clicked on it, saw the messages.
Clicked on "Hide Lint Messages".
Went to https://secure.phabricator.com/diffusion/ARC/browse/master/src/difference/ArcanistDiffUtils.php;5be54e.
Saw "Switch Commit to See Lint".
Clicked on it, saw the messages.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin…