Not automatically update the graph if custom node is updated

This submission is to fix MAGN-1426 [Design] Should Updating the custom node definition propagate the update of already placed custom node without Pressing Run.

The fix is, if a custom node is modified, the graph won't be updated immediately (so function definition won't be injected into the VM and the update won't be triggered). Instead, the graph sync data will be queued until user clicks "Run" button.