- Training offloading start function is separated into prepare_sender and preapre_receiver
- Change mix used variable name
- ml_pipeline_start is commonly used in start functions

Signed-off-by: hyunil park <[email protected]>

…sion_service

 and training_offloading_services to ml_service.

- Remove _ml_extension_invoke_new_data(), _invoke_event_new_data()
- Remove ml_extension_node_type_e, ml_extension_node_info_s
- Remove ml_training_offloading_node_type_e, ml_training_offloading_node_info_s
- Remove _ml_extension_pipeline_sink_cb(), _pipeline_sink_cb()
- Create _ml_service_invoke_event_new_data()
- Create ml_service_node_type_e, ml_service_node_info_s
- Create _ml_service_pipeline_sink_cb()
- Code clean: Change mix used variable name

Signed-off-by: hyunil park <[email protected]>