Support schema contexts

### Feature description

Currently, we're handling schema name collisions by prefixing subject names with a context name (which is the connector ID by default).

A better way to do would be using [Schema Contexts](https://docs.confluent.io/platform/current/schema-registry/schema-contexts-cp.html), however, the franz-go client that we're currently using doesn't support those. We'll open issues/feature requests in the franz-go repo detailing what needs to be done.