libobs: Add obs_data_save_json function

We keep having to repeat code for saving the json data to a file, so add
a helper function to help clean up some of that code.

libobs/obs-data.c

@@ -699,6 +699,18 @@ const char *obs_data_get_json(obs_data_t *data)
 	return data->json;
 }
 
+bool obs_data_save_json(obs_data_t *data, const char *file)
+{
+	const char *json = obs_data_get_json(data);
+
+	if (json && *json) {
+		return os_quick_write_utf8_file(file, json, strlen(json),
+				false);
+	}
+
+	return false;
+}
+
 static struct obs_data_item *get_item(struct obs_data *data, const char *name)
 {
 	if (!data) return NULL;

libobs/obs-data.h

@@ -67,6 +67,7 @@ EXPORT void obs_data_addref(obs_data_t *data);
 EXPORT void obs_data_release(obs_data_t *data);
 
 EXPORT const char *obs_data_get_json(obs_data_t *data);
+EXPORT bool obs_data_save_json(obs_data_t *data, const char *file);
 
 EXPORT void obs_data_apply(obs_data_t *target, obs_data_t *apply_data);