feat: improved rollup pipeline changes

[atarashansky]

Reason for Change

• Implement improved rollup algorithm - WMG pipeline #6399
• If the reason for this PR's code changes are not clear in the issue, state value/impact

Changes

• added a new pipeline step to generate a cell type ancestors fixture that will be used to perform the explode operation in the backend

Testing steps

• Added unit tests for the ancestors fixture.
• Test run of the pipeline is currently being run in rdev. This message will be updated upon completion to indicate success or failure.
  • See run here: https://us-west-2.console.aws.amazon.com/batch/home?region=us-west-2#jobs/ec2/detail/db36f520-37b1-42e5-922c-97de42b0b9e1

[github-actions]

Deployment Summary

• backend_url: https://pr-6419-backend.rdev.single-cell.czi.technology
• frontend_url: https://pr-6419-frontend.rdev.single-cell.czi.technology
• delete_db_task_definition_arn: arn:aws:ecs:us-west-2:***:task-definition/dp-rdev-pr-6419-deletion:1
• migrate_db_task_definition_arn: arn:aws:ecs:us-west-2:***:task-definition/dp-rdev-pr-6419-migration:1

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (f2674bd) 92.44% compared to head (f5b7289) 92.42%.

Files	Patch %	Lines
tests/unit/backend/wmg/fixtures/test_snapshot.py	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6419      +/-   ##
==========================================
- Coverage   92.44%   92.42%   -0.02%     
==========================================
  Files         179      179              
  Lines       14698    14702       +4     
==========================================
+ Hits        13587    13588       +1     
- Misses       1111     1114       +3     

Flag	Coverage Δ
unittests	92.42% <25.00%> (-0.02%)	⬇️

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[prathapsridharan]

LGTM