Room list notifications tweaks (#6106)

We decided against changing how unread activity is rendered in the room list, so the experiment and its developer option are no longer needed.
we have also added a notification settings entry for hiding the room list gray dots.

ElementX/Sources/Screens/Settings/NotificationSettingsScreen/NotificationSettingsScreenModels.swift

@@ -40,6 +40,7 @@ struct NotificationSettingsScreenViewStateBindings {
     var roomMentionsEnabled = false
     var callsEnabled = false
     var invitationsEnabled = false
+    var showAllRoomListActivity = true
     var alertInfo: AlertInfo<NotificationSettingsScreenErrorType>?
     var shouldShowAlertSounds = false
     var shouldShowCustomAlertTonePicker = false
@@ -93,6 +94,7 @@ enum NotificationSettingsScreenViewAction {
     case roomMentionChanged
     case callsChanged
     case invitationsChanged
+    case showAllRoomListActivityChanged
     case close
     case fixConfigurationMismatchTapped
     case selectAlertTone(NotificationTone)