[web] [refactor] destructure props in message preview component

Summary: no functionality changes. Just keeping the component consistent with the rest of the codebase and destructuring props.

Test Plan: message preview component still works like it did before changes.

Reviewers: atul, def-au1t, palys-swm

Reviewed By: palys-swm

Subscribers: ashoat, palys-swm, Adrian, karol-bisztyga

Differential Revision: https://phabricator.ashoat.com/D3504