feat(srp): add drawing settings override material seam

- add a managed DrawingSettings seam for scene draw authoring
- let builtin forward scene draws use an override material when provided
- wire DrawObjectsPass and RenderObjectsRendererFeature through the new settings

engine/src/Scripting/Mono/MonoScriptRuntime.cpp

@@ -24,6 +24,7 @@
 #include "Rendering/RenderPassGraphContract.h"
 #include "Rendering/RenderPipelineStageGraphContract.h"
 #include "Resources/BuiltinResources.h"
+#include "Core/Asset/ResourceManager.h"
 #include "Scene/Scene.h"
 #include "Scripting/ScriptComponent.h"
 #include "Scripting/ScriptEngine.h"
@@ -4590,7 +4591,8 @@ mono_bool
 InternalCall_Rendering_ScriptableRenderContext_DrawRenderersByDesc(
     uint64_t nativeHandle,
     int32_t scenePhase,
-    ManagedRendererListDescData* rendererListDescData) {
+    ManagedRendererListDescData* rendererListDescData,
+    MonoString* overrideMaterialPath) {
     ManagedScriptableRenderContextState* const state =
         FindManagedScriptableRenderContextState(nativeHandle);
     if (state == nullptr ||
@@ -4607,6 +4609,23 @@ InternalCall_Rendering_ScriptableRenderContext_DrawRenderersByDesc(
     drawSettings.rendererListDesc =
         *reinterpret_cast<const Rendering::RendererListDesc*>(
             rendererListDescData);
+    const std::string overrideMaterialPathUtf8 =
+        MonoStringToUtf8(overrideMaterialPath);
+    if (!overrideMaterialPathUtf8.empty()) {
+        drawSettings.overrideMaterial =
+            Resources::ResourceManager::Get().Load<Resources::Material>(
+                overrideMaterialPathUtf8.c_str());
+        if (!drawSettings.overrideMaterial.IsValid()) {
+            Debug::Logger::Get().Error(
+                Debug::LogCategory::Rendering,
+                (Containers::String(
+                     "ScriptableRenderContext DrawRenderers failed to load override material: ") +
+                 Containers::String(overrideMaterialPathUtf8.c_str()))
+                    .CStr());
+            return 0;
+        }
+    }
+
     return state->sceneRecorder->RecordSceneDrawSettings(
                drawSettings)
         ? 1