Make a URP shader compatible with the SRP Batcher

To ensure that a Shader is SRP Batcher compatible:

• Declare all Material properties in a single CBUFFER called UnityPerMaterial.
• Declare all built-in engine properties, such as unity_ObjectToWorld or unity_WorldTransformParams, in a single CBUFFER called UnityPerDraw.

For more information on the SRP Batcher, refer to the documentation on the Scriptable Render Pipeline (SRP) Batcher.