* Add response header filters to http-route config entry definitions
* Map response header filters from config entry when constructing route destination
* Support response header modifiers at the service level as well
* Update protobuf definitions
* Update existing unit tests
* Add response filters to route consolidation logic
* Make existing unit tests more robust
* Add missing docstring
* Add changelog entry
* Add response filter modifiers to existing integration test
* Add more robust testing for response header modifiers in the discovery chain
* Add more robust testing for request header modifiers in the discovery chain
* Modify test to verify that service filter modifiers take precedence over rule filter modifiers
Nathan Coleman