Disclose to joining users that they are using QSS

[holmesworcester]

Before we can release QSS in a form that people can use to join communities without a command line option, we should disclose that people are using QSS.

https://www.figma.com/design/8gOWYuzQPydMmIb09Cz8gh/Community-joining%2Fcreating-%2B-connection-type-(server%2FTor)?node-id=908-15917&t=8IgxxG3DfjROz5t9-4

We should also only support Quiet's own server at this point, and we should show an error message if someone uses a server other than our own server.

HW will provide language here.