Read jitsi server url from .well-known configuration

[Targunitoth]

Pull Request Checklist

PR for Issue #3443, depends on SDK Update
It would be kind if you could test and improve my PR.

• Changes has been tested on an Android device or Android emulator with API 16
• UI change has been tested on both light and dark themes
• Pull request is based on the develop branch
• Pull request updates CHANGES.rst
• Pull request includes screenshots or videos if containing UI changes
• Pull request includes a sign off

[Targunitoth]

I don't know, what I did wrong to get the Travis Cl build fail.
Also I testet my implementation and it seems like there is still a bug, the initUiAndData() Function is not always called.
The Problem is to get the non-static String mSession.getHomeServerConfig().getJitsiServerUri().toString(); to the static variable JITSI_SERVER_URL, which is used in 2 companion kotlin functions.

[bmarty]

Unfortunately, the Wellknown configuration returned when user logs in does not contains all the fields that are provided in a classical Wellknown request.
The doc has been updated: https://matrix.org/docs/spec/client_server/latest#post-matrix-client-r0-login

So I think this will not work. Was it working on your side?

[Targunitoth]

Maybe an SDK Upgrade was needed. Also I think this PR is obsolete due to #3462.

[MisterRager]

We definitely need this patch, too. The one I added is only good for finding currently active widgets, not for gathering information on how to widget if it's not there yet. Sorry for the slow response - I didn't have my personal laptop for a bit.

I could fix the patch if you want to get it landed faster.

[Targunitoth]

Feel free to fix it. I'm currently short on time.
The missing link is something like:
JITSI_SERVER_URL = mSession.getHomeServerConfig().getJitsiServerUri().toString();
To get a valid session and then get the non-static value into the static variable.