Notification sound for each profile

[morellik]

It would be helpful to have a different notification sound for each profile. Also, notifications between regular and DC emails could have different sounds.

[WofWca]

We had this MR #3583, but it was closed due to prioritization IIRC, so IMU we do want to implement this feature eventually.

[r10s]

also, feature requests should go to https://support.delta.chat/ - i think, to avoid fragmentation we should disable the github-discussions as in the other repos (also to not make moving away from github one day even harder :)