Moved test generation from DAG files into main functionality

[jmafoster1]

Now users can type python -m causal_testing -G... to generate tests rather than python causal_testing/testing/metamorphic_relation.py.

[github-actions]

🦙 MegaLinter status: ✅ SUCCESS

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ PYTHON	black	31		0	0.98s
✅ PYTHON	pylint	31		0	5.61s

See detailed report in MegaLinter reports

MegaLinter is graciously provided by

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.75%. Comparing base (a940927) to head (a51b66d).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #330      +/-   ##
==========================================
+ Coverage   95.69%   95.75%   +0.05%     
==========================================
  Files          27       27              
  Lines        1603     1624      +21     
==========================================
+ Hits         1534     1555      +21     
  Misses         69       69              

Files with missing lines	Coverage Δ
causal_testing/__main__.py	97.43% <100.00%> (+0.46%)	⬆️
causal_testing/main.py	95.98% <100.00%> (+0.09%)	⬆️
causal_testing/testing/metamorphic_relation.py	100.00% <100.00%> (ø)

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e7b8577...a51b66d. Read the comment docs.

🚀 New features to boost your workflow:

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

[f-allian]

@jmafoster1 All looks good! 👍🏼