Heuristic Sampling Improvements

[Eric-Vin]

Description

Improves heuristic sampling functionality in the veneer. Now everything should raise RejectionException, which is converted to an InvalidScenarioError at a higher level if appropriate.

Issue Link

#256

Checklist

• I have tested the changes locally via pytest and/or other means
• I have added or updated relevant documentation
• I have autoformatted the code with black and isort
• I have added test cases (if applicable)

Additional Notes

[abanuelo]

Looks great!

[dfremont]

I think the sense of the main test is backwards (rejections should ordinarily not be allowed at compile time), so we'd better add a test making sure it works correctly. I have a refactoring suggestion above too.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.27%. Comparing base (d7679fb) to head (2759488).
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #287      +/-   ##
==========================================
- Coverage   91.32%   91.27%   -0.06%     
==========================================
  Files          54       54              
  Lines       13515    13528      +13     
==========================================
+ Hits        12343    12348       +5     
- Misses       1172     1180       +8     

Files	Coverage Δ
src/scenic/domains/driving/roads.py	94.18% <100.00%> (+0.09%)	⬆️

... and 8 files with indirect coverage changes

[dfremont]

Looks good! If you want to fix the issue of having to set a fixed color in the test by changing DrivingObject.lane etc. to use self.position instead of self in this PR, go ahead; otherwise we can make a new one.

[Eric-Vin]

Went ahead and made the change. Please go ahead and take a final look and merge when you get the chance!