Add infrastructure for serialization tests

[pranavm-nvidia]

We should have some kind of infrastructure which will accept constructed Tripy objects and then run them through serialization/deserialization and check if the resulting object matches the original. The test would be of the form:

deserialized = json_utils.from_json(json_utils.to_json(obj))
assert obj.__dict__ == deserialized.__dict__

This will help us ensure we don't forget any fields in our serialization code.