This commit fixes the right click context menu options for videos. Now,
it contains "Reply", "Open With...", "Save Video As", "View Source" and
"Delete Message".
Furthermore, the auto video play widget of video messages in the room
history gets overlayed with
- a play icon in the center
- a message context menu button on the top right. On click, it opens
a popover. That popover contains the same options as the right click
context menu popover.
