This change is intended to make the redpanda implementation of the schema registry easily available on test containers.

The schema registry port `8081` was added to the list of exposed ports and a supporting method `getSchemaRegistryAddress` was added to easily use for configuring `schema.registry.url` serializer configuration.

A minor change on the internal advertised address was made as the `kafka` alias was not available within the container and the panda proxy was getting lost with the following message:
```
INFO  2022-10-17 19:08:37,164 [shard 0] kafka/client - broker.cc:41 - connected to broker:-1 - 0.0.0.0:29092
WARN  2022-10-17 19:08:37,176 [shard 0] kafka/client - broker.cc:52 - std::system_error: kafka: Not found
ERROR 2022-10-17 19:08:37,177 [shard 0] pandaproxy - service.cc:137 - Schema registry failed to initialize internal topic: kafka::client::broker_error ({ node: -1 }, { error_code: broker_not_available [8] })
```

Since this is only an internal advertised address and the `dev-container` is an alias to only one node, this should not be an issue. An alternative approach for configuring the `kafka` alias within the container node would be welcome.

Also, a simple test to check if the registry is available is made. Please let me know if you feel like we should actually perform some schema registration.

Describes how to retrieve the schema registry address

Schema registry tests for publishing and consuming new schemas.

The tests only cover the api availability. Further reference should follow the official documentation as this is a quite extensive / complex subject, which would require code generation, plugins to have as example while the [official documentation](https://docs.confluent.io/platform/current/schema-registry/index.html) is quite good.