feat(srp): add render state block scene draw overrides

- add managed RenderStateBlock authoring types and wire them through DrawingSettings
- let RenderObjectsRendererFeature author depth and stencil overrides for scene draws
- apply scene draw render state overrides inside builtin forward pipeline and document the stage plan

project/Assets/Scripts/ProjectRenderPipelineProbe.cs

@@ -143,6 +143,24 @@ namespace ProjectScripts
                                 "Unlit",
                             overrideMaterialPath =
                                 "Assets/New Material.mat",
+                            overrideRenderStateBlock =
+                                true,
+                            renderStateBlock =
+                                new RenderStateBlock
+                                {
+                                    mask =
+                                        RenderStateMask.Depth,
+                                    depthState =
+                                        new DepthState
+                                        {
+                                            writeEnabled = true,
+                                            compareFunction =
+                                                CompareFunction.LessEqual
+                                        },
+                                    stencilState =
+                                        StencilState.CreateDefault(),
+                                    stencilReference = 0
+                                },
                             overrideRenderQueueRange = true,
                             renderQueueRange =
                                 RenderQueueRange.Opaque,