Key backup returns (#1951)

* Converge on UserSessionFlowCoordinator logout confirmation

* Add logout confirmation screen strings to untranslated.

* Fix chat backup learn more URl fragment.

* Implement logout flows that check recovery and key backup for the last session

* Move logout confirmation screen strings to localazy

* Change encrypted timeline item copy to "Waiting for decryption key"

* Use different encrypted history banner based on key backup states

* Introduce a SettingsFlowCoordinator and implement navigation directly to the secure backup screen from the logout flows.

* Fix **mocked** secure backup controller flows

* Simplify encrypted history banner logic

* Address PR comments

ElementX/Sources/Screens/SecureBackup/SecureBackupKeyBackupScreen/View/SecureBackupKeyBackupScreen.swift

@@ -21,8 +21,6 @@ import SwiftUI
 struct SecureBackupKeyBackupScreen: View {
     @ObservedObject var context: SecureBackupKeyBackupScreenViewModel.Context
     
-    @ScaledMetric private var iconSize = 70
-    
     var body: some View {
         mainContent
             .padding()