Support latest PXT with GC (#1798)

* Enable gc and basic compilation fixes

* Add missing GC stuff

* Set microbit-dal version

* Disable jacdac in servo

* UTF fixes

* TS build fixes

* Auto-generated files update

* We only seem to have that much

* Fix for new new compiler

* Account for uninitialized scheduler

* Intialize memory allocator

* bump references

* updated package

* Set image tag, requires https://github.com/Microsoft/pxt/pull/5262

* updated project summaries

* Fixing block tests

libs/bluetooth/bluetooth.cpp

@@ -17,7 +17,7 @@ namespace bluetooth {
     void __log(String msg) {
         if (NULL == pHF2)
             pHF2 = new BLEHF2Service(*uBit.ble);
-        pHF2->sendSerial(msg->data, msg->length, false);
+        pHF2->sendSerial(msg->getUTF8Data(), msg->getUTF8Size(), false);
     }
 
     /**