Introduce certain React Components which may be used to write
cross-platform source code such as Audio like Web's audio, Container
like Web's div, Text like Web's p, etc.

Also move (native) avatar style to film-strip styles, since  that's where it
applies. This is analogous to how the large-view avatar is styled.

This reverts commit 739298c782.

They better represent if a participant has video available or not. There are
cases when even a participant in the last N set would not have video because it
disconnected momentarily, for example.