Restructure Python-based feeders

Today the top file in dbc2val contain a lot of switches depending on if databroker or val-server is used, like below. This could be refactored to simplify testing. One idea could be to put the databroker/val-server specific code in separate classes, so that we instantiate the "client-class" once and then just call methods on that client class.

Current code:

                      if self._server_type is ServerType.KUKSA_DATABROKER:
                        try:
                            self._provider.update_datapoint(target, value)
                        except kuksa_client.grpc.VSSClientError:
                            log.error(f"Error sending {target} to databroker", exc_info=True)
                            success = False
                    else:
                        # Using json.dumps to convert Python values to JSON, for example True -> true
                        resp=json.loads(kuksa.setValue(target, json.dumps(value)))
                        if "error" in resp:
                            log.error(f"Error sending {target} to kuksa-val-server: {resp['error']}")
                            success = False

Possible new code:

success = self._client.send(target,value)

Some of the code is duplicated for the upcoming ddsidl feeder (#61). We could possibly refactor them to avoid duplication by putting common code in common files.

eclipse / kuksa.val.feeders

Restructure Python-based feeders #62