Add external particle life sample

[SilverSpace505]

This is a sample showing a particle life simulation that runs on WebGPU. It uses spatial partitioning with atomic linked lists / counting sort to achieve larger numbers of particles.

The sample code itself has become quite large (it's around 2000 lines spread across multiple files and folders). So it's probably better as an external sample.

The reason i'm submitting this as a sample is because the simulation itself does use atomic linked lists and counting sort in an applied context to do spatial partitioning allowing for the simulation to avoid n^2 computations improving performance. This property of the sample could potentially make it a useful resource to others looking to develop their own simulations that involve spatial partitioning or particles.

I'm happy to make any changes that may be needed to contribute.
Please let me know whether this sample is appropriate for inclusion.

External sample: https://gpu-life.silverspace.io?sample
Repository: https://github.com/SilverSpace505/gpu-life

[kainino0x]

This is a very fun sample! I agree the algorithms involved here seem interesting so they'll be useful learning materials. LGTM but let me add one more reviewer in case there's anything I didn't think of.

[greggman]

looks great!