Update Participants UI in Conpherence Full
Summary: This shrinks the UI to fit more people in the participants list, useful for rooms. Also update the remove icon.
Test Plan:
Review a lot of people in a room, so so many.
{F354233}
Reviewers: epriestley, btrahan
Reviewed By: btrahan
Subscribers: Korvin, epriestley
Differential Revision: https://secure.phabricator.com/D12213