feat: Flysky PL18 Support (#4105)

Co-authored-by: raphaelcoeffic <raphael.coeffic@frafos.com>
Co-authored-by: rotorman <risto.koiva@web.de>
Co-authored-by: Xy201207 <yaoxu@flysky.com>
Co-authored-by: Peter Feerick <peter.feerick@gmail.com>

radio/src/targets/simu/opentxsimulator.cpp

@@ -712,6 +712,8 @@ class OpenTxSimulatorFactory: public SimulatorFactory
       return Board::BOARD_TARANIS_X9LITE;
 #elif defined(PCBNV14)
       return Board::BOARD_FLYSKY_NV14;
+#elif defined(PCBPL18)
+      return Board::BOARD_FLYSKY_PL18;
 #else
       return Board::BOARD_TARANIS_X9D;
 #endif