Show Encryption Authenticity warnings on messages in the timeline. (#3051)

* Initial implementation.

* Add developer option for showing timeline item authenticity.

* Refactor code to use new SendInfo.Status.

---------

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

ElementX/Sources/Application/AppSettings.swift

@@ -47,6 +47,7 @@ final class AppSettings {
         case publicSearchEnabled
         case fuzzyRoomListSearchEnabled
         case pinningEnabled
+        case timelineItemAuthenticityEnabled
     }
     
     private static var suiteName: String = InfoPlistReader.main.appGroupIdentifier
@@ -284,6 +285,9 @@ final class AppSettings {
     
     @UserPreference(key: UserDefaultsKeys.pinningEnabled, defaultValue: false, storageType: .userDefaults(store))
     var pinningEnabled
+    
+    @UserPreference(key: UserDefaultsKeys.timelineItemAuthenticityEnabled, defaultValue: false, storageType: .userDefaults(store))
+    var timelineItemAuthenticityEnabled
         
     #endif