Replace watermark logo with animated gif

Now we have the fairmeeting logo as watermark.png in /usr/share/jitsi-meet/images .

It is quite dominant for the whole conference. It could be replaced by an animated gif, see the test here:

Proposed scenes:

1. fairmeeting logo
2. headset recommendation
3. use LAN or full WLAN
4. read the FAQs
5. fairmeeting logo
6. nothing
7. fairmeeting logo after 5', 10' for some seconds
8. A coin goes into the pay what you can box
9. repeat 2-3 times

visual only, no text

Current size in CSS:

watermark {
   width: 186px;
   height: 74px;
}