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/securebackup/impl/src/main/res/values-ro/translations.xml

@@ -33,7 +33,6 @@
   <string name="screen_recovery_key_confirm_error_content">"Vă rugăm să încercați din nou să confirmați accesul la backup."</string>
   <string name="screen_recovery_key_confirm_error_title">"Cheie de recuperare incorectă"</string>
   <string name="screen_recovery_key_confirm_key_description">"Dacă aveți o cheie de securitate sau o frază de securitate, aceasta va funcționa și ea."</string>
-  <string name="screen_recovery_key_confirm_key_label">"Cheie de recuperare sau cod de acces"</string>
   <string name="screen_recovery_key_confirm_key_placeholder">"Introduceți…"</string>
   <string name="screen_recovery_key_confirm_lost_recovery_key">"Ați pierdut cheia de recuperare?"</string>
   <string name="screen_recovery_key_confirm_success">"Cheia de recuperare confirmată"</string>