The styling for review request entries (reviews, etc.) and comment

headers now use Flexbox, which helps us manage styles more consistently

and avoids some hacks and workarounds to get things to line up in mobile

and desktop modes correctly.
This is necessary for some in-progress work on user badges, which impact

the layout of this area.

Tested the styling for reviews, changes, and status updates, in both

expanded and collapsed mode.
Tested these on both mobile and desktop at various widths.
Tested with in-progress changes for user badges.
Checked alignment on the text to make sure everything lined up

correctly.