Improve 3D global illumination demo

- Readd LightmapGI example.
- Allow toggling between the Once and Always update modes for the
  ReflectionProbe.
- Add a Decal node to act as a blob shadow for dynamic objects.
- Halve SSAO intensity for a better apperance in the demo's flat,
  bright surfaces.
- Halve ambient light sky contribution when using the disabled
  or lightmap-based GI modes. This prevents the level's shaded areas
  from looking too bright and blue (with lightmaps, this change only
  affects dynamic objects.)
- Enable FXAA and debanding for a better appearance.

3d/global_illumination/project.godot

@@ -11,6 +11,7 @@ config_version=5
 [application]
 
 config/name="Global Illumination"
+config/description="This demo showcases Godot's global illumination systems: LightmapGI, VoxelGI, SDFGI, ReflectionProbe and screen-space effects like SSAO and SSIL."
 run/main_scene="res://test.tscn"
 config/features=PackedStringArray("4.0")
 config/icon="res://icon.png"
@@ -20,6 +21,10 @@ config/icon="res://icon.png"
 window/stretch/mode="canvas_items"
 window/stretch/aspect="expand"
 
+[editor]
+
+export/convert_text_resources_to_binary=true
+
 [filesystem]
 
 import/blender/enabled=false
@@ -31,7 +36,7 @@ cycle_gi_mode={
 "events": [Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":0,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":0,"physical_keycode":32,"unicode":0,"echo":false,"script":null)
 ]
 }
-toggle_reflection_probe={
+cycle_reflection_probe_mode={
 "deadzone": 0.5,
 "events": [Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":0,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":0,"physical_keycode":82,"unicode":0,"echo":false,"script":null)
 ]
@@ -78,5 +83,7 @@ common/enable_pause_aware_picking=true
 
 [rendering]
 
+anti_aliasing/quality/screen_space_aa=1
+anti_aliasing/quality/use_debanding=true
 quality/shadows/filter_mode=2
 environment/default_environment="res://default_env.tres"