Support "WireMock Scenarios" feature

At the moment it is possible to generate wiremock snippets that both document error scenarios and success scenarios for the same URL path. Later on the client the behaviour is non-deterministic on which of these snippets are getting used.

We need a way (like tagging the wiremock snippets) that let's the client specify which of these snippets to use as part of the fixture setup. If that is not possible, either reject or warn when user wants to generate two wiremock snippets of the same URL path.