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/core/pxt.json

@@ -18,6 +18,8 @@
         "pxt-helpers.ts",
         "helpers.ts",
         "pinscompat.ts",
+        "configkeys.h",
+        "gc.cpp",
         "codal.cpp",
         "images.cpp",
         "basic.cpp",
@@ -50,6 +52,7 @@
     "yotta": {
         "optionalConfig": {
             "microbit-dal": {
+                "fiber_user_data": 1,
                 "bluetooth": {
                     "private_addressing": 0,
                     "advertising_timeout": 0,