ui: show username instead of RingID everywhere
Issue generated from Tuleap's migration script. Originally submitted by: Adrien Béraud (adrienberaud)
On every client:
* If there is an account registered username, it should be shown/shared instead of the RingID on front page/share link etc. (except QR code).
* A username lookup should always be performed on every RingID in the conversation history,
if a name is found it should be shown instead of the RingID.
* In a call/conversation, the contact registered name should be shown instead of the RingID. An advanced menu option (not shown by default) should still allow to copy the RingID.