Key backup Rust API adoption (#1952)

* Adopt Rust side secure backup APIs (incomplete, based on poljar/backup-pr)

* Implement the home screen recovery key confirmation banner.

* Update with the latest Rust changes.

The loading button for .unknown was incorrect. It should be treated as disabled.

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Co-authored-by: Doug <douglase@element.io>

ElementX/Sources/Services/Client/ClientProxy.swift

@@ -96,7 +96,7 @@ class ClientProxy: ClientProxyProtocol {
         notificationSettings = NotificationSettingsProxy(notificationSettings: client.getNotificationSettings(),
                                                          backgroundTaskService: backgroundTaskService)
         
-        secureBackupController = SecureBackupController()
+        secureBackupController = SecureBackupController(encryption: client.encryption())
 
         client.setDelegate(delegate: ClientDelegateWrapper { [weak self] isSoftLogout in
             self?.hasEncounteredAuthError = true

ElementX/Sources/Services/Client/MockClientProxy.swift

@@ -44,6 +44,7 @@ class MockClientProxy: ClientProxyProtocol {
         let secureBackupController = SecureBackupControllerMock()
         secureBackupController.underlyingRecoveryKeyState = .init(CurrentValueSubject<SecureBackupRecoveryKeyState, Never>(.disabled))
         secureBackupController.underlyingKeyBackupState = .init(CurrentValueSubject<SecureBackupKeyBackupState, Never>(.enabled))
+        secureBackupController.isLastSessionReturnValue = .success(false)
         return secureBackupController
     }()