key backup: Add a dedicated section to settings

#2193

Still WIP

Riot/Modules/Settings/KeyBackup/SettingsKeyBackupViewState.swift

@@ -0,0 +1,33 @@
+/*
+ Copyright 2019 New Vector Ltd
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+ */
+
+import UIKit
+
+/// SettingsKeyBackup view state
+///
+/// - checkingBackup: Load current backup on the homeserver
+/// - checkError: Fail to load current backup data
+/// - noBackup: There is no backup on the homeserver
+/// - backup: There is a valid backup on the homeserver. All keys have been backed up to it
+/// - backupAndRunning: There is a valid backup on the homeserver. Keys are being sent to it
+/// - backupButNotVerified: There is a backup on the homeserver but it has not been verified yet
+enum SettingsKeyBackupViewState {
+    case checkingBackup
+    case noBackup
+    case backup(MXKeyBackupVersion, MXKeyBackupVersionTrust)
+    case backupAndRunning(MXKeyBackupVersion, MXKeyBackupVersionTrust, Progress)
+    case backupButNotTrusted(MXKeyBackupVersion, MXKeyBackupVersionTrust)
+}