fix: enable scenario termination from closing display

[abanuelo]

Description

Fix that allows users to manually close out display via the UI and continue subsequent simulations to continue. Here is a video illustrating the working changes

pygame_fixed.mov

Issue Link

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

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 85.96%. Comparing base (0232e6f) to head (bde9c32).

Files	Patch %	Lines
src/scenic/simulators/newtonian/simulator.py	60.00%	2 Missing ⚠️
src/scenic/core/simulators.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #238   +/-   ##
=======================================
  Coverage   85.96%   85.96%           
=======================================
  Files         144      144           
  Lines       24768    24777    +9     
=======================================
+ Hits        21292    21300    +8     
- Misses       3476     3477    +1     

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