feat(arbiter-engine): Run method for agents and messager echo example

[Autoparallel]

Give an overview of the tasks completed
This PR adds the ability to have a world ran via World::run(). To show how this works, see arbiter_engine::examples::tests, specifically the base_simulation() function. This will run a simulation that loads an agent's engine with a messager as both a collector and executor which allows for this agent to receive external stimulus and communicate within this layer (potentially to other agents). Externally, "Start" is sent to the agent which kicks off a loop where the agent repeatedly echoes "Hello, world!" every second. This does not exit gracefully yet, use ctrl + c. It is a POC.

Link to issue(s) that this PR closes
Closes #745

[0xJepsen]

Really nice

[codecov]

Codecov Report

Attention: 215 lines in your changes are missing coverage. Please review.

Comparison is base (eb5a7f8) 11.52% compared to head (6015ac2) 52.63%.
Report is 23 commits behind head on main.

Files	Patch %	Lines
arbiter-engine/src/examples.rs	0.00%	90 Missing ⚠️
arbiter-engine/src/agent.rs	0.00%	58 Missing ⚠️
arbiter-engine/src/world.rs	0.00%	47 Missing ⚠️
arbiter-engine/src/messager.rs	0.00%	18 Missing ⚠️
arbiter-core/src/middleware/mod.rs	86.66%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #746       +/-   ##
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+ Coverage   11.52%   52.63%   +41.10%     
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  Files          32       36        +4     
  Lines        7047     7277      +230     
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+ Hits          812     3830     +3018     
+ Misses       6235     3447     -2788     

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