EI: Link to MAS for sign-out in MSC3824 OIDC-aware mode

[hughns]

This is a sub item from #7644

In the case of OIDC-aware clients, you cannot sign out of other sessions via the device manager in Element iOS anymore. Instead, users will need to be guided towards the MAS UI to take this actions.

MSC3824 now describes this requirement including a format of a deep link structure to pass the device ID: ?action=session_end&device_id=<device_id>

[pmaier1]

• We should add wording to let the user understand what's happening: "You will be redirected to your server's authentication provider to complete sign out."
• If the server doesn't advertise an account management URL, the client should show a message saying that the functionality is currently unavailable and the user should contact the administrator.

[Velin92]

Reopened to address the following comment

• We should add wording to let the user understand what's happening: "You will be redirected to your server's authentication provider to complete sign out."
• If the server doesn't advertise an account management URL, the client should show a message saying that the functionality is currently unavailable and the user should contact the administrator.

[Velin92]

• We should add wording to let the user understand what's happening: "You will be redirected to your server's authentication provider to complete sign out."
• If the server doesn't advertise an account management URL, the client should show a message saying that the functionality is currently unavailable and the user should contact the administrator.

I used alerts to display these dialogues.
Here is the PR with some videos for reference, these may be useful for android @pmaier1

#7658