Add Account fails when full URI of server instance used

[DavidBurela]

Jerboa Version 0.0.33

Describe the bug When joining Lemmy for the first time, it is natural to:

1. sign up for an instance using a web browser
2. copy/paste the domain from browser into the app

But if you have https:// at the beginning of the instance name, Jerboa errors that it is not a Lemmy instance.

To Reproduce

• Sign up in the browser to a community (eg. https://lemmy.world)
• copy/paste the server domain into Jerboa (eg. https://lemmy.world)
• Fails with https://lemmy.world is not a Lemmy instance
• remove the https://, and it logs in successfully

Suggestions

1. Warn the user if a protocol is specified in the instance name http://, https://, etc
2. Strip the protocol, and attempt to connect