[web] Add loadable video component
Summary:
Extracted the video logic from D7902 as this will also be needed for modals.
This component is intended to display thumbnail while video is loading. And while thumbnail is decrypted/loaded, the thumbhash is displayed. The component also supports encrypted thumbnails.
Test Plan: Tested together with D7902
Reviewers: ashoat, atul, ginsu, inka
Reviewed By: ashoat
Subscribers: tomek
Differential Revision: https://phab.comm.dev/D7946