Set Environment's Ao Channal Effect to 1.0 by default

"Ao Channel Affect" was defaulting to 0, giving unexpected results.
This meant that as soon as you set an AO texture on a material,
there will no longer be SSAO on that material.

This led many users to think that Godot didn't support using
SSAO and AO textures at the same time.

This closes godotengine#43957.

doc/classes/Environment.xml

@@ -215,7 +215,7 @@
 		<member name="ss_reflections_max_steps" type="int" setter="set_ssr_max_steps" getter="get_ssr_max_steps" default="64">
 			The maximum number of steps for screen-space reflections. Higher values are slower.
 		</member>
-		<member name="ssao_ao_channel_affect" type="float" setter="set_ssao_ao_channel_affect" getter="get_ssao_ao_channel_affect" default="0.0">
+		<member name="ssao_ao_channel_affect" type="float" setter="set_ssao_ao_channel_affect" getter="get_ssao_ao_channel_affect" default="1.0">
 			The screen-space ambient occlusion intensity on materials that have an AO texture defined. Values higher than [code]0[/code] will make the SSAO effect visible in areas darkened by AO textures.
 		</member>
 		<member name="ssao_bias" type="float" setter="set_ssao_bias" getter="get_ssao_bias" default="0.01">

scene/resources/environment.h

@@ -151,7 +151,7 @@ class Environment : public Resource {
 	float ssao_intensity = 1.0;
 	float ssao_bias = 0.01;
 	float ssao_direct_light_affect = 0.0;
-	float ssao_ao_channel_affect = 0.0;
+	float ssao_ao_channel_affect = 1.0;
 	SSAOBlur ssao_blur = SSAO_BLUR_3x3;
 	float ssao_edge_sharpness = 4.0;
 	void _update_ssao();

servers/rendering/rasterizer_rd/rasterizer_scene_rd.h

@@ -740,7 +740,7 @@ class RasterizerSceneRD : public RasterizerScene {
 		float ssao_intensity = 1;
 		float ssao_bias = 0.01;
 		float ssao_direct_light_affect = 0.0;
-		float ssao_ao_channel_affect = 0.0;
+		float ssao_ao_channel_affect = 1.0;
 		float ssao_blur_edge_sharpness = 4.0;
 		RS::EnvironmentSSAOBlur ssao_blur = RS::ENV_SSAO_BLUR_3x3;