Rageshakes impossible if unable to get cross signing key (Eg, access token is invalid)

### Steps to reproduce

1. Create & login with a user on a server
2. Delete the server state
3. Attempt to use the browser to start a call (nothing works)
4. Try to logout ([nothing works, no error](https://github.com/vector-im/element-call/issues/676))
5. Try to rageshake (screenshot below)

Filing this separately because being unable to rageshake is slightly different than just not being able to log out - the rageshake creation code could simply gracefully handle failures to get debugging information (in this screenshot, I think it's cross-signing key status) and still submit something useful. I haven't checked but I could imagine other failures eg server is unavailable that could block rageshakes.

The linked issue #676 needs more UI work and consideration of how to logout properly.

### Outcome

#### What did you expect?
To logout at some point, and to be able to rageshake the failure to logout.

#### What happened instead?
No logout, no rageshaking.


### Operating system

Ubuntu

### Browser information

Firefox

### URL for webapp

Version: v0.3.14 on internal server

### Will you send logs?

No

Start by reproducing the listed flow in Firefox on Ubuntu, then trace the rageshake creation path and its attempt to retrieve cross-signing key status. The issue names no files or tests; done means a rageshake can still be submitted with useful debugging information when that lookup or another server-dependent step fails.

Written by the indexing model from the issue text.