Some UI improvements to the reviewers plugin

Use plugin provided font styles.

Make sure that repo command aligns well with other repo commands.
Specifically follow change 344117 and add a description about what
the command is doing.

Screenshot https://imgur.com/a/UpigN7P

Release-Notes: skip
Bug: Issue 16115
Change-Id: I33fd9ee812a05d1790d57651cf422ad393fd91e4