feat: readiness check (#1839)

* feat: readiness check

* fix: no need for query param

* docs: add a note

* chore: move the readyness check to its own endpoint

* docs(cr): add godoc

Co-authored-by: Joel Speed <Joel.speed@hotmail.co.uk>

pkg/middleware/stored_session_test.go

@@ -793,3 +793,7 @@ func (f *fakeSessionStore) Clear(rw http.ResponseWriter, req *http.Request) erro
 	}
 	return nil
 }
+
+func (f *fakeSessionStore) VerifyConnection(_ context.Context) error {
+	return nil
+}