Add regression test case

This pull request added a language test case for defect [MAGN-5311: GC: The old element is not deleted when input is switched to another subgrap] (http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-5311)

The following steps demonstrate this issue:
  1. Use ``Point.ByCoordinates()`` node to create a point
  2. Delete this node and run
  3. In debug mode, verify geometry's Dispose() method is not invoked.

@riteshchandawar for your review.