Generate contract testing coverage reports for both consumers and providers

[Ben Sayers]

The swagger-mock-validator is in a position where it could generate coverage reports for a contract. Some useful things it could report on:

• For providers: which endpoints are not being used by any consumers
• For consumers and providers: which status codes are not being tested by consumers

As part of this story an investigation should be done to find out if there are any standard formats we could represent this information in. We would also need to decide what the changes to the cli would look like.

[Ben Sayers]

We do not have any known consumers for this feature so closing this as won't fix. We are happy to reconsider if a concrete use case is brought to our attention, let us know if you have one!