feat(arbiter-engine): run multiple worlds in parallel

[Autoparallel]

Give an overview of the tasks completed
We now have a Universe struct which can hold on to a collection of Worlds. It provides a means to run all of these worlds in parallel. More fine tuning and features can be added later.

Link to issue(s) that this PR closes
Closes #505

[codecov]

Codecov Report

Attention: 29 lines in your changes are missing coverage. Please review.

Comparison is base (ba9c0ed) 16.50% compared to head (4b9d59e) 16.77%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
arbiter-core/src/data_collection.rs	0.00%	9 Missing ⚠️
arbiter-engine/src/agent.rs	27.27%	8 Missing ⚠️
arbiter-engine/src/machine.rs	0.00%	6 Missing ⚠️
arbiter-engine/src/universe.rs	95.41%	5 Missing ⚠️
arbiter-engine/src/world.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #826      +/-   ##
==========================================
+ Coverage   16.50%   16.77%   +0.27%     
==========================================
  Files          38       39       +1     
  Lines       29993    30124     +131     
==========================================
+ Hits         4950     5053     +103     
- Misses      25043    25071      +28     

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[0xJepsen]

This seems straightforward enough.