[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/gui/modules/file_browser.h

@@ -0,0 +1,39 @@
+/**
+ * @file file_browser.h
+ * GUI: FileBrowser view module API
+ */
+
+#pragma once
+
+#include "m-string.h"
+#include <gui/view.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct FileBrowser FileBrowser;
+typedef void (*FileBrowserCallback)(void* context);
+
+FileBrowser* file_browser_alloc(string_ptr result_path);
+
+void file_browser_free(FileBrowser* browser);
+
+View* file_browser_get_view(FileBrowser* browser);
+
+void file_browser_configure(
+    FileBrowser* browser,
+    const char* extension,
+    bool skip_assets,
+    const Icon* file_icon,
+    bool hide_ext);
+
+void file_browser_start(FileBrowser* browser, string_t path);
+
+void file_browser_stop(FileBrowser* browser);
+
+void file_browser_set_callback(FileBrowser* browser, FileBrowserCallback callback, void* context);
+
+#ifdef __cplusplus
+}
+#endif