Possibilty to change username when using azure

[chileocat]

When using Azure as login mechanism, there is no chance to change the username.

So when we connect to another user, they will see our e-mailaddress. Using local accounts, there is still a possibilty to change the username as mentioned here #334.

Any possibility to get this also working? At the moment the only workaround I see is using the display-name override described here #277

[rustdesk]

@fufesou Using email as username does not very make sense, it expose users' privacy. Please how about other vendors or app use azure.