refs https://github.com/TryGhost/Toolbox/issues/320
- This is an **MVP** to be able to intercept and match webhook request
snapshots. The concept is similar to the one used in API E2E tests using
same "matchBodySnapshot" and other "match*" methods to test the webhook
**request** data
- Next up here would be:
1. Header matcher
2. Mocking more than one webhook (and doing something nicer with the way
the fixture data is inserted, does this logic belong to the mock-receiver?
