refactor(swagger-client): fix import of helpers (#6190)
Import of helpers from swagger-client worked because of the fact
that commonjs exports are basically an objects that can be destructured.
Whenever swagger-client switches to ES6 imports as primary mechanism
of webpack consuptions imports like that will fail. This change makes
sure that import mechanism is both compatible with ES6 and commonjs
import systems.
Along with that rename default import of swagger-client
to more appropriate SwaggerClient.