Test that `Address` is enforcing canonical encodings

[ruhatch]

Background

We have to enforce canonical encodings on Address, but we're currently not testing that we've covered all the parts that need to.

Proposed Solution

Add a test to make sure that all the parts of the Address are enforcing canonicity.

[edsko]

This could perhaps be considered to be part of #662. Same comment applies: Marking as medium priority for Byron, but I can't quite judge the consequences of not checking this. @dcoutts might want to reprioritize.