I ported the predicates showing difference between points-to and
type-tracking, since it's helpful to see the list of differences,
instead of having to parse expectations!
The import doesn't actually work the intended way, so running
```
$ python python/ql/test/experimental/library-tests/CallGraph/test.py
```
will procude no output. but our extractor will extract the things we need, so
for a quick fix this will need to suffice.
