Webusb pairing updates (#5081)

* pairing 'connect step: swap to gif

* trim pair dialog img in pair step

* use current 'firmware upd needed' png for successfully connected

* remove now unused values, bump pxt

package.json

@@ -45,6 +45,6 @@
     },
     "dependencies": {
         "pxt-common-packages": "10.4.8",
-        "pxt-core": "8.6.27"
+        "pxt-core": "8.6.29"
     }
 }

pxtarget.json

@@ -619,16 +619,13 @@
 
             "downloadMenuHelpURL" : "/device/usb",
             "downloadHelpURL" : "/device/usb",
-            "firmwareHelpURL": "/device/usb/webusb/troubleshoot",
             "troubleshootWebUSBHelpURL": "/device/usb/webusb/troubleshoot",
             "incompatibleHardwareHelpURL": "/device/v2",
 
             "dragFileImage": "/static/download/transfer.png",
-            "connectDeviceImage": "/static/download/connect.png",
-            "selectDeviceImage": "/static/download/pair.png",
-            "connectionSuccessImage": "/static/download/connected.png",
-            "checkFirmwareVersionImage": "/static/download/firmware.png",
-            "checkUSBCableImage": "/static/download/connect.png",
+            "connectDeviceImage": "/static/download/connect-microbit.gif",
+            "selectDeviceImage": "/static/download/pair-browser.png",
+            "connectionSuccessImage": "/static/download/successfully-paired.png",
             "incompatibleHardwareImage": "/static/download/incompatible.png"
         },
         "winAppDeprImage": "/static/winapp.PNG",