Frontend updates (#22327)

* add optional field widget

adds a switch to enable nullable fields like skip_motion_threshold

* config field updates

add skip_motion_threshold optional switch
add fps back to detect restart required

* don't use ternary operator when displaying motion previews

the main previews were being unnecessarily unmounted

* lazy mount motion preview clips to reduce DOM overhead

web/src/components/config-form/theme/frigateTheme.ts

@@ -26,6 +26,7 @@ import { FfmpegArgsWidget } from "./widgets/FfmpegArgsWidget";
 import { InputRolesWidget } from "./widgets/InputRolesWidget";
 import { TimezoneSelectWidget } from "./widgets/TimezoneSelectWidget";
 import { CameraPathWidget } from "./widgets/CameraPathWidget";
+import { OptionalFieldWidget } from "./widgets/OptionalFieldWidget";
 
 import { FieldTemplate } from "./templates/FieldTemplate";
 import { ObjectFieldTemplate } from "./templates/ObjectFieldTemplate";
@@ -73,6 +74,7 @@ export const frigateTheme: FrigateTheme = {
     audioLabels: AudioLabelSwitchesWidget,
     zoneNames: ZoneSwitchesWidget,
     timezoneSelect: TimezoneSelectWidget,
+    optionalField: OptionalFieldWidget,
   },
   templates: {
     FieldTemplate: FieldTemplate as React.ComponentType<FieldTemplateProps>,