Use Committee middleware to validate Chat API responses

This adds a new initializer for Committee that sets up the middleware
to validate the responses from the Chat API against the OpenAPI specification.

It is scoped to the Chat API V0 namespace and is configured to raise
errors if the response does not match the specification so we're alerted
via sentry rather than it failing silently.

I've set strict_reference_validation to true to ensure that our OpenAPI
schema is valid. This will be enforced in the next major release of
Committee.

You can read more about the configuration here:
https://github.com/interagent/committee?tab=readme-ov-file#committeemiddlewareresponsevalidation

I've also added a test to ensure that the middleware is being applied to
the endpoint. We can extract this into a shared example for future endpoints.

Author: davidgisbey

config/initializers/committee.rb

@@ -0,0 +1,7 @@
+require "committee"
+
+Rails.application.config.middleware.use Committee::Middleware::ResponseValidation,
+                                        schema_path: "docs/api_openapi_specification.yml",
+                                        prefix: "/api/v0",
+                                        strict_reference_validation: true,
+                                        raise: true

spec/requests/api/v0/conversations_spec.rb

@@ -52,5 +52,20 @@
         expect(response).to have_http_status(:forbidden)
       end
     end
+
+    context "when the response returned does not conform to the OpenAPI specification" do
+      it "raises an error and returns the invalid params in the error message" do
+        answer = create(:answer, question:)
+        eager_loaded_answer = Answer.includes(:sources, :feedback).find(answer.id)
+        answer_blueprint = AnswerBlueprint.render_as_hash(eager_loaded_answer)
+        answer_blueprint.delete(:created_at)
+        allow(AnswerBlueprint).to receive(:render).and_return(answer_blueprint)
+
+        expect { get api_v0_answer_question_path(conversation, question) }
+          .to raise_error(Committee::InvalidResponse) do |error|
+            expect(error.message).to match(/missing required parameters: created_at/)
+          end
+      end
+    end
   end
 end