Extend Plugin Hook Helpers

• Insomnia Version: 5.15.0 • Operating System: OS X 10.13.4 Details Related in principle to what I would _like_ to be able to do as a plugin developer is have some control over the UI when dealing with responses. As outlined in that issue, my overall aim here is to automatically validate the response body against a spec file the user supplies in their environment config (atm swagger). There are a few scenarios that the validation could invoke: - there are 1 (or more) errors with the actual validation - schema does not match - the path is missing from the spec (so it is not complete and we cannot validate) - the path exists, the response body matches the spec, we have positive feedback At the moment, the only real way of displaying feedback to the user is via an alert. This isn't great on a number of fronts - first of all, you don't want to alert to a success and second of all, you may have multiple errors which does not fit the dialog sty…