refactor: Break apart monolithic configuration schema (#1977)

[skip ci]

src/config/schema/actions/custom/internal.ts

@@ -0,0 +1,16 @@
+import { z } from 'zod';
+import { advancedCameraCardCustomActionsBaseSchema } from './base';
+
+// An action that can be used internally to call a callback (it is not possible
+// for the user to pass this through via the configuration).
+export const INTERNAL_CALLBACK_ACTION = '__INTERNAL_CALLBACK_ACTION__';
+export const internalCallbackActionConfigSchema =
+  advancedCameraCardCustomActionsBaseSchema.extend({
+    advanced_camera_card_action: z.literal(INTERNAL_CALLBACK_ACTION),
+
+    // The callback is expected to be called with a CardController API object.
+    callback: z.function().args(z.any()).returns(z.promise(z.void())),
+  });
+export type InternalCallbackActionConfig = z.infer<
+  typeof internalCallbackActionConfigSchema
+>;