[FL-2491] File browser GUI module (#1237)

* File browser module and test app
* nfc: Add support for saved files in subdirectories
* nfc: Use helper function to get shadow path when loading data
* File browser dialog integration pt.1
* File browser dialog integration pt.2
* Gui,Dialogs: drop file select
* Correct use of dynamic string_t(string_ptr)

Co-authored-by: Yukai Li <yukaili.geek@gmail.com>
Co-authored-by: Aleksandr Kutuzov <alleteam@gmail.com>

applications/infrared/infrared_app.h

@@ -251,6 +251,8 @@ public:
     /** Main class destructor, deinitializes all critical objects */
     ~InfraredApp();
 
+    string_t file_path;
+
     /** Path to Infrared directory */
     static constexpr const char* infrared_directory = "/any/infrared";
     /** Infrared files extension (remote files and universal databases) */