Remove PointsTo Edge Class (#1717)

* Import Node Tag & Remove Points To
* In Joern's new import resolution, descriptions of entities referred to by imports are described by `Tag` nodes. Since `Import` nodes cannot be tagged, their optional call node is tagged instead. Not all languages use call imports so this excludes languages like Java. This allows import nodes to be tagged to avoid this exclusion.
* Removed the `POINTS_TO` edge as it is no longer used, this was initially brought in as an experimental alias analysis edge but realistically this would likely be done on-the-fly or via `Tag` nodes until a better motivation for this edge is given.

* Remove `PointsTo` Edge Class
This should fix the failing test, seems that this removal will complete PR #1716

Author: DavidBakerEffendi