[FL-2423] Storage: blocking dir open (#1083)

* Storage: more unit tests
* Storage: blocking dir open, differentiate file and dir when freed.

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

applications/storage/storage.h

@@ -24,6 +24,7 @@ typedef enum {
     StorageEventTypeCardUnmount,
     StorageEventTypeCardMountError,
     StorageEventTypeFileClose,
+    StorageEventTypeDirClose,
 } StorageEventType;
 
 typedef struct {
@@ -65,6 +66,12 @@ bool storage_file_close(File* file);
  */
 bool storage_file_is_open(File* file);
 
+/** Tells if the file is a directory
+ * @param file pointer to a file object
+ * @return bool true if file is a directory
+ */
+bool storage_file_is_dir(File* file);
+
 /** Reads bytes from a file into a buffer
  * @param file pointer to file object.
  * @param buff pointer to a buffer, for reading