[FL-1931, FL-2005] SubGhz: migration in flipper file format (#807)

* SubGhz: add save key in flipper file format
* [FL-2005] SubGhz: fix stored signals cannot be deleted
* SubGhz: add load key in flipper file format
* SubGhz: fix syntax
* SubGhz: fix bad file upload
* Storage: add function to get the next free filename
* SubGhz: add save RAW  in flipper file format
* SubGhz: add load RAW in flipper file format
* SubGhz: refactoring protocol
* SubGhz: refactoring scene
* SubGhz: fix SubGhzNotificationState define
* Makefile: proper comapre for FORCE

Co-authored-by: あく <alleteam@gmail.com>

applications/storage/storage.h

@@ -262,6 +262,22 @@ bool storage_simply_remove_recursive(Storage* storage, const char* path);
  */
 bool storage_simply_mkdir(Storage* storage, const char* path);
 
+/**
+ * @brief Get next free filename.
+ * 
+ * @param storage
+ * @param dirname 
+ * @param filename 
+ * @param fileextension 
+ * @param nextfilename return name
+ */
+void storage_get_next_filename(
+    Storage* storage,
+    const char* dirname,
+    const char* filename,
+    const char* fileextension,
+    string_t nextfilename);
+
 #ifdef __cplusplus
 }
 #endif