Remove c++ macros that are moving to common packages (#1953)

* (probably) fix PXT_BUFFER_DATA, need to set up docker to test

* switch to adding new macros

* more macros and rename some

* get data length in bytes

* remove macros that were moved to common packages

* bump common packages to include reqd pr

package.json

@@ -45,7 +45,7 @@
     "@types/web-bluetooth": "0.0.4"
   },
   "dependencies": {
-    "pxt-common-packages": "6.5.19",
+    "pxt-common-packages": "6.5.20",
     "pxt-core": "5.9.3"
   }
 }