Add more video & audio codecs to Nextcloud Talk iOS

**Is your feature request related to a problem? Please describe.**
Janus, part of the [standalone signaling server](https://github.com/strukturag/nextcloud-spreed-signaling), can be configured to use modern and efficient codecs like VP9,AV1,H265 etc. And the Nextcloud Talk infrastructure can work perfectly fine with this.

Using Nextcloud Talk in a Browser, even mobile Safari, one can make use of these codecs.

The issue appears form Desktop to iOS - iOS to iOS works, but i’m not sure which codecs are being used

**Describe the solution you'd like**
Add codec support which is on par with mobile Safari, mainly this would be h265, h264 and VP9
Right now, receiving video is blank (grey backdrop without user icon), whereas video sent from iOS works.

**Describe alternatives you've considered**
Not using the iOS app any more, instead only mobile safari