[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/u2f/u2f_data.h

@@ -6,6 +6,8 @@ extern "C" {
 
 #include <furi.h>
 
+bool u2f_data_check();
+
 bool u2f_data_cert_check();
 
 uint32_t u2f_data_cert_load(uint8_t* cert);