[native] Play button for video messages

Summary: Added play button for video messages

Test Plan: Looked fine on iOS Simulator: https://blob.sh/atul/comm-play-button.png

Reviewers: ashoat, palys-swm

Reviewed By: ashoat

Subscribers: KatPo, zrebcu411, Adrian, subnub

Differential Revision: https://phabricator.ashoat.com/D834