[FL-1059] T5577 write (#463)

* Api-hal-gpio: extend init functions
* App Lfrfid: separate protocol layer
* App Lfrfid: write EM key scene
* App Lfrfid: syntax fix

applications/lf-rfid/lf-rfid-app.cpp

@@ -143,4 +143,8 @@ RfidReader* LfrfidApp::get_reader() {
 
 RfidTimerEmulator* LfrfidApp::get_emulator() {
     return &emulator;
+}
+
+RfidWriter* LfrfidApp::get_writer() {
+    return &writer;
 }