Add webrtc support

[dpazdan]

MetaMask browser is not compatible with Webrtc

If for example you open https://test.webrtc.org/ you can see that it doesn't work.

related to support ticket: 34641

[EtDu]

Directly related #1042

[EtDu]

@omnat Is this something we really want to add?

It seems to work in Android but we need to modify a few things to grant it the proper permissions.

For iOS, we'd have to implement the capability on the webview since it doesn't support it out of the box.

We could spend a long time trying to solve this problem, so I don't think it's worth our efforts.

Also check out #1042 because in a situation like this, we should inform them to use our soon to be wallet_scanQrCode RPC method
cc @andrepimenta cause you're working on the browser at the moment