WS-507: More foundation-laying for ingestion manifest builder

• Fleshed out classes
• Added example files
• Got started on first test

stole lots from the archive version

apps/cli/executables/pexable/ingest_envoy/ingest_envoy/ingestion_manifest.py

@@ -2,7 +2,7 @@
 
 from pathlib import Path
 
-from .utility_classes import (
+from .utilities import (
     Telescope,
     ScienceProduct,
 )