Remove SessionData.needsVerification as the source of truth for session verification status (#2748)

* Remove `SessionData.needsVerification` as the source of truth for session verification status.

- Use the Rust SDK `EncryptionService.verificationState()` instead, but always waiting for the first 'known' result (either verified or not, discarding 'unknown').
- Add a workaround in the super rare case when reading this value gets stuck somehow. We'll assume the user is not verified in that case.
- Make `DefaultFtueService.getNextStep` and dependent checks `suspend`.
- Make the `skip` button use a value in the session preferences instead.

* Log exception when the verification status can't be loaded

Co-authored-by: Benoit Marty <benoit@matrix.org>

* Fix review comments

---------

Co-authored-by: Benoit Marty <benoit@matrix.org>

libraries/preferences/api/src/main/kotlin/io/element/android/features/preferences/api/store/SessionPreferencesStore.kt

@@ -34,5 +34,8 @@ interface SessionPreferencesStore {
     suspend fun setRenderTypingNotifications(enabled: Boolean)
     fun isRenderTypingNotificationsEnabled(): Flow<Boolean>
 
+    suspend fun setSkipSessionVerification(skip: Boolean)
+    fun isSessionVerificationSkipped(): Flow<Boolean>
+
     suspend fun clear()
 }