feat: add RAK4631 USB serial bridge target

variants/rak4631/platformio.ini

@@ -95,6 +95,25 @@ build_src_filter = ${rak4631.build_src_filter}
   +<helpers/bridges/RS232Bridge.cpp>
   +<../examples/simple_repeater>
 
+[env:RAK_4631_repeater_bridge_usbserial]
+extends = rak4631
+build_flags =
+  ${rak4631.build_flags}
+  -D DISPLAY_CLASS=SSD1306Display
+  -D ADVERT_NAME='"USB Bridge"'
+  -D ADVERT_LAT=0.0
+  -D ADVERT_LON=0.0
+  -D ADMIN_PASSWORD='"password"'
+  -D MAX_NEIGHBOURS=50
+  -D WITH_RS232_BRIDGE=bridgeSerial
+  -D WITH_USB_SERIAL_BRIDGE
+  -D CFG_TUD_CDC=2
+  -UENV_INCLUDE_GPS
+build_src_filter = ${rak4631.build_src_filter}
+  +<helpers/ui/SSD1306Display.cpp>
+  +<helpers/bridges/RS232Bridge.cpp>
+  +<../examples/simple_repeater>
+
 [env:RAK_4631_repeater_bridge_rs232_serial2]
 extends = rak4631
 build_flags =