Update Review Bot extension configuration to use new admin styling.
Review Request #10990 — Created April 7, 2020 and submitted
This change moves the Review Bot extension configuration over to the new
components for styling in the admin UI. As part of this, I've simplified
the layout a little bit so that the main configuration items are
together in a single fieldset, rather than splitting them into two
Verified the appearance and functionality of the extension config.
What does this end up looking like on RB3?