Add forced logout flow when the proxy is no longer available (#3458)

* Add `MatrixClient.isSlidingSyncProxySupported` function

* Update localazy strings

* Modify `ErrorDialog` to have an `onSubmit` call, which will be used for the submit action.

Also make the title text optional and dismissing the dialog by tapping outside/going back configurable.

* Check if a forced migration to SSS is needed because the proxy is no longer available.

In that case, display the non-dismissable dialog and force the user to log out after enabling SSS.

* Enable native/simplified sliding sync by default.

* Refactor the login to make sure we:

1. Always try native/simplified sliding sync login first, if available.
2. Then, if it wasn't available or failed with an sliding sync not supported error, try with the proxy instead (either discovered proxy or forced custom one).

* Move logic to `LoggedInPresenter` and the UI to `LoggedInView`

* Update screenshots

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Co-authored-by: ElementBot <benoitm+elementbot@element.io>

features/login/impl/src/main/res/values-nl/translations.xml

@@ -35,10 +35,4 @@
   <string name="screen_server_confirmation_message_register">"Dit is waar je gesprekken zullen worden bewaard — net zoals je een e-mailprovider zou gebruiken om je e-mails te bewaren."</string>
   <string name="screen_server_confirmation_title_login">"Je staat op het punt je aan te melden bij %1$s"</string>
   <string name="screen_server_confirmation_title_register">"Je staat op het punt een account aan te maken op %1$s"</string>
-  <string name="screen_waitlist_message">"Er is momenteel veel vraag naar %1$s op %2$s. Kom over een paar dagen terug naar de app en probeer het opnieuw.
-
-Bedankt voor je geduld!"</string>
-  <string name="screen_waitlist_message_success">"Welkom bij %1$s!"</string>
-  <string name="screen_waitlist_title">"Je bent er bijna."</string>
-  <string name="screen_waitlist_title_success">"Je bent binnen."</string>
 </resources>