App assumes that the server name is the host of the server URL

### Steps to reproduce

Try to use Element Call with a homeserver where the server name is different from the host that the CS API actually resides on

### Outcome

#### What did you expect?

The app should use the right server name

#### What happened instead?

Room redirects are broken, and the wrong server name is shown on the registration and login forms.

### Operating system

NixOS unstable

### Browser information

Firefox 106.0.2

### URL for webapp

_No response_

### Will you send logs?

No