WS-507: Fleshing out classes, adding examples, getting started on first test

...s/pexable/ingest_envoy/ingest_envoy/ingestion_manifest.py

...e/ingest_envoy/ingest_envoy/ingestion_manifest_builder.py

...bles/pexable/ingest_envoy/ingest_envoy/utility_classes.py

...ingest_envoy/test/examples/evla_calibration_manifest.json

.../pexable/ingest_envoy/test/examples/evla_eb_manifest.json

...exable/ingest_envoy/test/examples/image_set_manifest.json

...exable/ingest_envoy/test/examples/quicklook_manifest.json

...le/ingest_envoy/test/examples/vlass_catalog_manifest.json

...bles/pexable/ingest_envoy/test/test_evla_ing_manifests.py