Migrate impc_etl/jobs/load/impc_web_api/impc_datasets_metadata_mapper.py to use Airflow

[ficolo]

• The input asset matches the output of the required DAG
• The output assets match the output path of the luigi task
• The DAG runs locally
• Documentation in place

Dependencies:

• ImpressToParameterMapper (pipeline_parquet)
• StatsResultsMapper (stats_results_parquet)

Input Parquet Files:

• pipeline_parquet
• stats_results_parquet

Output:

• datasets_metadata_service_json