Adding model variable attribute validation

[davidorme]

Description

This PR adds a function in main.py that checks that the variables added to data during a model __init__ or first _update actually match the vars_populated_at_init and vars_populated_at_first_update attributes of the model. These currently aren't validated and this seems like the simplest way to try and keep these attributes up to date.

I think this could be extended to verify the other var_ attributes too, but keeping the variable population correct matters to resolving the model running order.

Fixes #1337

Type of change

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist

• Make sure you've run the pre-commit checks: $ pre-commit run -a
• All tests pass: $ poetry run pytest

Further checks

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works
• Relevant documentation reviewed and updated

[codecov-commenter]

Codecov Report

❌ Patch coverage is 59.25926% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.85%. Comparing base (177aaaf) to head (ab232fb).

Files with missing lines	Patch %	Lines
virtual_ecosystem/main.py	59.25%	11 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1338      +/-   ##
===========================================
- Coverage    94.99%   94.85%   -0.14%     
===========================================
  Files           71       71              
  Lines         7366     7392      +26     
===========================================
+ Hits          6997     7012      +15     
- Misses         369      380      +11     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[jacobcook1995]

This seems like a sensible change to me!