ingestion manifest creation for EVLA CAL ingestion only

Next step is refactoring to IngestionManifestIF and having EVLA CAL ingestion manifest implement it, but I wanted to get this out there for review.

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

@@ -75,6 +75,8 @@ class ScienceProduct:
 
     @classmethod
     def init_from_filename(cls, filename: str) -> ScienceProduct:
+        # TODO: Determine how we want ScienceProduct objects to be initialized. From filename? or from metadata
+        #  like above?
         raise NotImplementedError
 
     def get_sp_pattern(self):