allow microbit-robot simulator (#5405)

* allow microbit-robot simulator

Adds microbit-robot repo to allowed simulator paths

* register message simulator

* Update targetconfig.json

pxtarget.json

@@ -252,6 +252,12 @@
                 "localHostUrl": "http://localhost:8000/tools/makecode-sim?webusb=0&parentOrigin=$PARENT_ORIGIN$",
                 "aspectRatio": 1.22,
                 "permanent": true
+            },
+            "robot": {
+                "url": "https://microsoft.github.io/microbit-robot/?parentOrigin=$PARENT_ORIGIN$",
+                "localHostUrl": "http://localhost:8000/?parentOrigin=$PARENT_ORIGIN$",
+                "aspectRatio": 1.22,
+                "permanent": true
             }
         },
         "boardDefinition": {