Do avatar placeholder in SwiftUI, Add AvatarViewModel, Add dependency injection for MxMediaManager dependency.

Riot/Modules/Room/NotificationSettings/UIKit/RoomNotificationsSettingsCell.swift

@@ -41,16 +41,3 @@ extension RoomNotificationSettingsCell: Themable {
         selectedBackgroundView?.backgroundColor = theme.selectedBackgroundColor
     }
 }
-
-fileprivate extension RoomNotificationState {
-    var title: String {
-        switch self {
-        case .all:
-            return VectorL10n.roomNotifsSettingsAllMessages
-        case .mentionsAndKeywordsOnly:
-            return VectorL10n.roomNotifsSettingsMentionsAndKeywords
-        case .mute:
-            return VectorL10n.roomNotifsSettingsNone
-        }
-    }
-}