Add management command to compare DVC and database-backed datasets

[tituomin]

Description

Add a management command called compare_dataset which can be used to:

• find datasets which have data both in DVC and the database
• for a single dataset at a time, examine how the data differs in detail for a dataset which has data both in DVC and the database.

Screenshots/Videos (if applicable)

N/A

Related issue

https://app.asana.com/1/1201243246741462/project/1206017643443542/task/1212662157746701?focus=true

Requirements, dependencies and related PRs

N/A

Additional Notes

Internal tool, read-only use, non-critical.

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✅ Pre-Merge Checklist

Type of Change

• Set the PR's label to match the nature of this change

Testing

• Built Unit tests (unit tests added/updated)
• Built E2E tests (if applicable. E2E tests added/updated)
• Authorization is tested (permissions and access controls verified)
• Manually tested locally (functionality verified)

  Manual testing instructions

  Look at ./manage.py compare_dataset --help for info

Internationalization & Accessibility

• New strings are translatable (all user-facing text uses i18n)
• Accessibility standards met (WCAG compliance, screen reader support)

Dependencies

• Dependencies are merged (if applicable. If the change depends on other PRs e.g. kausal_common)

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Screenshots/Videos (if applicable)

N/A

Additional Notes

N/A

[kausal-code-coverage]

Codecov Report

❌ Patch coverage is 87.00000% with 13 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
nodes/datasets.py	12.50%	7 Missing ⚠️
nodes/dataset_diff.py	93.47%	3 Missing and 3 partials ⚠️

@@            Coverage Diff             @@
##             main     #236      +/-   ##
==========================================
+ Coverage   41.21%   41.34%   +0.13%     
==========================================
  Files         287      288       +1     
  Lines       34471    34570      +99     
  Branches     5079     5095      +16     
==========================================
+ Hits        14206    14292      +86     
- Misses      19114    19124      +10     
- Partials     1151     1154       +3     

Flag	Coverage Δ
e2e-tests	12.78% <0.00%> (-0.04%)	⬇️
unittests	34.14% <87.00%> (+0.15%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
nodes/dataset_diff.py	93.47% <93.47%> (ø)
nodes/datasets.py	39.29% <12.50%> (-0.43%)	⬇️

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[jtuomist]

I tested this and it works just fine. I cannot think of improvements, ready to merge.