Chunking sql export queries, coverage

[dogversioning]

This PR makes the following changes:

• Exporter is rewritten to use pyarrow to enable large file exports
  • This required regenerating export example data
• Added coverage action to CI
• Added additional tests to clear coverage threshold
• Removed 'all' as a study target since it was increasingly not useful
• Removed remnants of old study creation mechanism

Checklist

• [X] Consider if documentation (like in docs/) needs to be updated
• [X] Consider if tests should be added
• [X] Update template repo if there are changes to study configuration

[github-actions[bot]]

☂️ Python Coverage

current status: ✅

Overall Coverage

Lines	Covered	Coverage	Threshold	Status
1854	1768	95%	90%	🟢

New Files

No new covered files...

Modified Files

File	Coverage	Status
cumulus_library/actions/exporter.py	97%	🟢
cumulus_library/cli.py	96%	🟢
cumulus_library/cli_parser.py	100%	🟢
cumulus_library/databases.py	96%	🟢
TOTAL	97%	🟢

updated for commit: 7526933 by action🐍