[FL-2226] BadUSB, U2F: missing assets error (#979)

* badusb, u2f: showing error screen if assets are missing
* BadUsb: remove dead code
* U2F: remove dead code

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

applications/bad_usb/bad_usb_script.c

@@ -159,8 +159,6 @@ static bool ducky_altchar(const char* charcode) {
     uint8_t i = 0;
     bool state = false;
 
-    //TODO: numlock
-
     FURI_LOG_I(WORKER_TAG, "char %s", charcode);
 
     furi_hal_hid_kb_press(KEY_MOD_LEFT_ALT);