Reduce bottom toolbar gap (2)

Merge pull request #281 from peer-calls/jeremija/video-preview

Tweaks for v4.2.1 and new features

Implement a better video grid (#251)

The new video grid supports fixed aspect ratios and will not resize the
video like it was done previously. The new layout is enabled
only when there are more than three participants. Users have a choice of
picking the three modes in the settings: AUTO (the new default), LEGACY
(the old default) and ASPECT (the new mode).

We can now also have a menu on the top videos toolbar that flips over
the edge of the parent container with defined height. On the other side,
this position is only defined once so if a window is resized, the
fixed-positioned dropdown will stay in place. We have a dropdown
backdrop so it's not the end of the world, but it's a compromise.

Fix an issue with toolbar on Firefox for Android due to tooltips being
too wide, for some reason it added extra margins on the bottom/right.

Merge pull request #278 from peer-calls/issue-277

Upgrade dependencies

Add single-click mute/camera toggle

Closes #271

Fix device dropdown on some Android devices

Some android devices do not support multiple calls to `getUserMedia`
with different `deviceId`s set, possibly because of the limitations in
the USB bus size when large sensors are used.

We can't call `stop` because that would invalidate the whole WebRTC
track; Want to be able to call `replaceTrack` on the peer connection to
quickly change the camera without renegotation, so as a workaround we'll
create a dummy black canvas video track and replace the video track.
When we replace this track, the existing real video track will be
stopped and we can safely call `getUserMedia` again.

Tested and verified on latest versions of Chrome and Firefox on Samsung
Galaxy A52s.

Disable insertable streams by default (#264)

Chrome started crashing with SIGSEGV when insertable streams were
enabled in Mesh network mode. Since the insertable streams only really
work on Chrome, it did not make sense to keep it enabled by default.
Also, the insertable streams currently only works with VP8 codec, it's
broken when using the H264, which is the default when SFU mode is
enabled.

Users who wish to enable insertable streams can do so by explicitly
setting the following environment variable:

    PEERCALLS_FRONTEND_ENCODED_INSERTABLE_STREAMS=true

Or the following YAML config option:

    frontend.encodedInsertableStreams: true

This is why corporations build their own native clients if they want to
support additional features.

Also, fix src/client/index-simple.tsx for mesh mode.

Closes #263.