Support for Meta Depth API for occlusion

[Ayfel]

Describe the problem

We would like to use the newer Graphic Tools shader together with the depth API occlusion features from Meta Quest headsets

Describe the solution you'd like

Add support to the depth api occlusion to the Graphic Tools Standard Shader as described here https://github.com/oculus-samples/Unity-DepthAPI

Describe alternatives you've considered

Editing locally those shaders

Additional context