Make filament segmentation shader distinct colors optional.

Previously we were computing at material update time a color for the geom based of it's
segid. This made segids unrecoverable from the resulting buffer. With this change
we allow SceneView creators to specify if they want the segmentation buffer to be purely
for visualization with distinct colors.

PiperOrigin-RevId: 840016870
Change-Id: I5920f248ace0901023e6545c7d8dd2b23f9aa397

src/experimental/studio/app.cc

@@ -164,6 +164,7 @@ App::App(int width, int height, std::string ini_path,
     render_config.load_asset = &App::LoadAssetCallback;
     render_config.load_asset_user_data = this;
     render_config.enable_gui = true;
+    render_config.use_distinct_segmentation_colors = true;
 #if defined(USE_FILAMENT_OPENGL)
     render_config.graphics_api = mjGFX_OPENGL;
 #elif defined(USE_FILAMENT_VULKAN)