feat: process RC packets back from CRSF module as trainer input (#5724)

i.e. allow head tracker data to be relayed via backpack!

radio/src/storage/yaml/yaml_datastructs_funcs.cpp

@@ -1329,6 +1329,7 @@ static const struct YamlIdStr enum_TrainerMode[] = {
   {  TRAINER_MODE_MASTER_BLUETOOTH, "MASTER_BT"  },
   {  TRAINER_MODE_SLAVE_BLUETOOTH, "SLAVE_BT"  },
   {  TRAINER_MODE_MULTI, "MASTER_MULTI"  },
+  {  TRAINER_MODE_CRSF, "MASTER_CRSF"  },
   {  0, NULL  }
 };