dal6 integration v1 (#1227)

* dal6 integration v1

* updating stack size

* fix gatt_table_size option

libs/bluetooth/pxt.json

@@ -20,6 +20,12 @@
                     "enabled": 1
                 }
             }
+        },
+        "optionalConfig": {
+            "microbit-dal": {
+                "stack_size": 1280,
+                "gatt_table_size": "0x700"
+            }
         }
     },
     "installedVersion": "vzlhfd"

libs/core/pxt.json

@@ -59,7 +59,6 @@
                     "pairing_mode": 1,
                     "whitelist": 1,
                     "security_level": "SECURITY_MODE_ENCRYPTION_NO_MITM",
-                    "gatt_table_size": "0x700",
                     "partial_flashing": 1
                 }
             }