Issue #153: Move initial data generation to rewarder

[Mark2000]

Description

Closes #153

Small change to move initial data generation to be defined with rest of data system instead of scenario.

Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [X] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

How should this pull request be reviewed?

• [ ] By commit
• [X] All changes at once

How Has This Been Tested?

Please describe the tests that you ran to verify your changes.

Passes Tests

• [X] Unit tests pytest --cov bsk_rl --cov-report term-missing tests/unittest
• [X] Integrated tests pytest --cov bsk_rl --cov-report term-missing tests/integration
• [X] Documentation builds cd docs; make html

Test Configuration

• Python: 3.10
• Basilisk: 3.2
• Platform: Mac

Checklist:

• [X] My code follows the style guidelines of this project (passes Black, ruff, and isort)
• [X] I have performed a self-review of my code
• [X] I have commented my code in hard-to-understand areas
• [X] I have made corresponding changes to the documentation and release notes
• [X] Commit messages are atomic, are in the form Issue #XXX: Message and have a useful message
• [X] My changes generate no new warnings
• [X] I have added tests that prove my fix is effective or that my feature works
• [X] If I changed an example ipynb, I have locally rebuilt the documentation