Add utility functions for removing nodes from catalogue graph

[StepanBrychta]

What does this change?

• Adds utility functions to remove nodes from the catalogue graph. These are needed whenever we do a catalogue graph reindex which involves removing concepts/works. See Reindex to remove duplicate concept ids platform#5912.
• Adds the option to pass CATALOGUE_SNAPSHOT_URL as an environment variable when extracting catalogue concepts/works. This is needed so that we can extract works/concepts from a dev snapshot instead of a prod snapshot. See this PR.
• Extracts source concept 'description' from the catalogue graph and indexes it into the concepts index. See Concepts API: Implementation of RFC; Update graph ingestor to index description platform#5971.
• Fixes a bug in the catalogue concepts extractor which caused Subjects not to be extracted.

How to test

How can we measure success?

Have we considered potential risks?

[github-actions]

☂️ Python Coverage

current status: ✅

Overall Coverage

Lines	Covered	Coverage	Threshold	Status
1890	1623	86%	0%	🟢

New Files

No new covered files...

Modified Files

File	Coverage	Status
catalogue_graph/src/clients/base_neptune_client.py	44%	🟢
catalogue_graph/src/config.py	100%	🟢
catalogue_graph/src/ingestor_loader.py	83%	🟢
catalogue_graph/src/models/catalogue_concept.py	100%	🟢
catalogue_graph/src/models/indexable_concept.py	84%	🟢
catalogue_graph/src/sources/catalogue/concepts_source.py	100%	🟢
catalogue_graph/src/transformers/catalogue/concepts_transformer.py	94%	🟢
catalogue_graph/src/transformers/catalogue/raw_concept.py	97%	🟢
catalogue_graph/src/transformers/catalogue/raw_work.py	100%	🟢
TOTAL	89%	🟢

updated for commit: 2479dcc by action🐍