Tools: Do a CubeOrange build with EKF2 as part of CI

need to build at least one ChibiOS-based board to be sure we haven't killed things

.github/workflows/test_chibios.yml

@@ -156,6 +156,7 @@ jobs:
             build-options-defaults-test,
             signing,
             CubeOrange-PPP,
+            CubeOrange-EKF2,
             SOHW,
             Pixhawk6X-PPPGW,
             new-check,

Tools/scripts/build_ci.sh

@@ -327,6 +327,14 @@ for t in $CI_BUILD_TARGET; do
         continue
     fi
 
+    if [ "$t" == "CubeOrange-EKF2" ]; then
+        echo "Building CubeOrange with EKF2 enabled"
+        $waf configure --board CubeOrange --enable-ekf2
+        $waf clean
+        $waf copter
+        continue
+    fi
+
     if [ "$t" == "SOHW" ]; then
         echo "Building CubeOrange-SOHW"
         Tools/scripts/sitl-on-hardware/sitl-on-hw.py --board CubeOrange --vehicle copter --simclass MultiCopter