Creating performance benchmark suite for collision detection

# What could be improved
It would be great to have a benchmark harness for the collision detection system.

# Why should this be improved
So that it is easier to know if you're making improvements or regressions, and also a good test bed to try out new broadphase algorithms.

# Any risks?
No change to the library code, so no risk.

# More information
This could possibly be used:
https://pub.dev/packages/benchmark_harness