Spatial mesh shaders

Describe the problem

MRTK2 has a few shaders for the spatial mesh that should be ported to Graphics Tools.

Describe the solution you'd like

We should move all shaders and supporting assets/scripts for this feature: https://docs.microsoft.com/en-us/windows/mixed-reality/mrtk-unity/mrtk2/features/rendering/pulse-shader?view=mrtkunity-2022-05 to this repository.

We will also want docs and samples to go along with these features.

Describe alternatives you've considered

We might also want to ensure at minimum these effects are also possible with Graphics Tools: https://github.com/microsoft/MixedReality-GraphicsTools-Unreal/blob/main/Docs/SpatialPerception.md

Additional context

We should check for updated MRDL designs for spatial meshes before proceeding.

Inizia esaminando la documentazione di MRTK2 pulse-shader e il riferimento Unreal SpatialPerception.md collegato nell’issue, quindi verifica la presenza di design MRDL aggiornati per gli spatial meshes. Il lavoro è completo quando gli spatial-mesh shaders e gli assets/scripts di supporto sono stati portati in questo repository, insieme alla documentazione e ai samples corrispondenti, coprendo gli effetti minimi identificati nel riferimento Unreal.