reworked developer tools with diagnostics, storage viewers and release-capable debug overlays

lib/view/pages/settings/data/default_settings.dart

@@ -70,8 +70,6 @@ class DefaultSettings {
     fileViewSettings: FileViewSettings(alwaysOpenExternally: Platform.isIOS),
     notificationSettings: NotificationSettings(enabled: true),
     devToolsSettings: DevToolsSettings(
-      checkerboardOffscreenLayers: false,
-      checkerboardRasterCacheImages: false,
       showPerformanceOverlay: false,
       marianumConnectEndpoint: MarianumConnectEndpoint.live,
       marianumConnectCustomUrl: '',