Add support for service load plugin discovery for AvroConverter, JsonSchemaConverter, ProtobufConverter

[yeikel]

Hi team,

I am trying to leverage KIP-898: Modernize Connect plugin discovery but some of the components do not have the necessary setup:

Sample error

.apache.kafka.connect.errors.ConnectException: One or more plugins are missing ServiceLoader manifests may not be usable with plugin.discovery=service_load: [
file:/usr/share/java/acl/       io.confluent.connect.avro.AvroConverter converter       undefined
file:/usr/share/java/acl/       io.confluent.connect.json.JsonSchemaConverter   converter       undefined
file:/usr/share/java/acl/       io.confluent.connect.protobuf.ProtobufConverter converter       undefined
]
Read the documentation at https://kafka.apache.org/documentation.html#connect_plugindiscovery for i