Static Shadow Caster (from hdrp) flag does nothing

Steps to reproduce

1. Create a new project or import an existing one using Unity 2021.3 LTS or newer
2. Add a 3D object to the scene and select it
3. Under the Mesh Renderer component, inspect the Static Shadow Caster flag

Expected behavior

• Enabling Static Shadow Caster flag allows user to specify which objects will be marked as static in a cached shadow map

Actual behavior

• Static Shadow Caster flag does not work in URP, and is only supported in custom SRPs. Cached shadows maps in URP are still not supported at the time of writing

Notes

• Observed in 2021.3.33f1 and all newer Unity releases
• Leaving this option exposed sets wrong expectations and can be confusing to our users
• Recommend hiding this option, and only exposing it once cached shadowmap support lands in URP
• For custom SRP users, allow them to access this flag via the API