SSGINode: New node for screen-space global illumination. (#31839)

* SSGINode: New node for screen-space global illumination.

* E2E: Add example to exception list.

* Example: Improve presets.

Author: Mugen87

examples/files.json

@@ -418,6 +418,7 @@
 		"webgpu_postprocessing_smaa",
 		"webgpu_postprocessing_sobel",
 		"webgpu_postprocessing_ssaa",
+		"webgpu_postprocessing_ssgi",
 		"webgpu_postprocessing_ssr",
 		"webgpu_postprocessing_traa",
 		"webgpu_postprocessing_transition",