move top-level modules into a real package

chromy/handlers/add_data.py

@@ -0,0 +1,9 @@
+from argparse import Namespace
+
+from chromy.utilities import ingest_file
+
+
+def handle_add_data(args: Namespace) -> int:
+    records_added = ingest_file(args.collection, args.file)
+    print(f"Added {records_added} records to collection '{args.collection}'.")
+    return 0