[QE] Create our own login and validator callback library to integrate Kafka with OAuth

Kafka supports authentication using SASL OAUTHBEARER mechanism. However, it doesn't fully implement the OAuth authentication. We will need to supply JARs with our own Login (client side) and Validator (server side) callbacks. These callback should integrate with our OAuth infrastructure in the way we choose to. In our case it should be mainly Keycloak, but we should aim to support any OAuth servers available (e.g. Hydra and whatever else there is).