Feature: Allow schema registry processor to use latest schema

### Feature description

The processor `encodewithschema` allows you to configure a subject and version. This means that updating the schema to a new version requires a change in the pipeline configuration and restarting the pipeline. We could support for the version to be configured as `latest` and have a period after which we invalidate the local cached schema. This would trigger the download of the schema in regular intervals, allowing us to always use the latest schema for the specified subject without restarting and reconfiguring the pipeline.