Warn users that the server may be being blocked if they can't connect to it.

[ara4n]

Steps to reproduce

1. Go to Russia
2. Try to install Element X
3. Get flooded with errors
4. Blame Element, rather than realise that it's because Russia is currently blocking access to matrix.org:

https://explorer.ooni.org/domain/matrix-client.matrix.org?since=2024-08-25&until=2024-09-25&probe_cc=RU

Outcome

What did you expect?

If the client can't connect to the server (which is quite common, due to captive wifi, internet blocking and general bad connectivity) we should handle it gracefully and warn the user that the connection to the server may be blocked, rather than emit whatever scary errors are confusing people.

What happened instead?

Apparently, scary errors. Haven't checked myself, but in practice the users are confused.

This issue twinned with element-hq/element-x-ios#3470