Use opaque rendering pipeline for alpha hash materials

This has several benefits:

- Transparency sorting issues inherent to alpha blending no longer occur.
- Alpha hash materials can now cast shadows (also works with
  GeometryInstance3D Transparency's property for alpha hash materials).
- Higher performance.

drivers/gles3/storage/material_storage.cpp

@@ -3234,6 +3234,9 @@ void SceneShaderData::set_code(const String &p_code) {
 
 	actions.usage_flag_pointers["ALPHA"] = &uses_alpha;
 	actions.usage_flag_pointers["ALPHA_SCISSOR_THRESHOLD"] = &uses_alpha_clip;
+	// Use alpha clip pipeline for alpha hash/dither.
+	// This prevents sorting issues inherent to alpha blending and allows such materials to cast shadows.
+	actions.usage_flag_pointers["ALPHA_HASH_SCALE"] = &uses_alpha_clip;
 	actions.render_mode_flags["depth_prepass_alpha"] = &uses_depth_pre_pass;
 
 	actions.usage_flag_pointers["SSS_STRENGTH"] = &uses_sss;

servers/rendering/renderer_rd/forward_clustered/scene_shader_forward_clustered.cpp

@@ -111,6 +111,9 @@ void SceneShaderForwardClustered::ShaderData::set_code(const String &p_code) {
 
 	actions.usage_flag_pointers["ALPHA"] = &uses_alpha;
 	actions.usage_flag_pointers["ALPHA_SCISSOR_THRESHOLD"] = &uses_alpha_clip;
+	// Use alpha clip pipeline for alpha hash/dither.
+	// This prevents sorting issues inherent to alpha blending and allows such materials to cast shadows.
+	actions.usage_flag_pointers["ALPHA_HASH_SCALE"] = &uses_alpha_clip;
 	actions.render_mode_flags["depth_prepass_alpha"] = &uses_depth_pre_pass;
 
 	actions.usage_flag_pointers["SSS_STRENGTH"] = &uses_sss;

servers/rendering/renderer_rd/forward_mobile/scene_shader_forward_mobile.cpp

@@ -112,6 +112,9 @@ void SceneShaderForwardMobile::ShaderData::set_code(const String &p_code) {
 
 	actions.usage_flag_pointers["ALPHA"] = &uses_alpha;
 	actions.usage_flag_pointers["ALPHA_SCISSOR_THRESHOLD"] = &uses_alpha_clip;
+	// Use alpha clip pipeline for alpha hash/dither.
+	// This prevents sorting issues inherent to alpha blending and allows such materials to cast shadows.
+	actions.usage_flag_pointers["ALPHA_HASH_SCALE"] = &uses_alpha_clip;
 	actions.render_mode_flags["depth_prepass_alpha"] = &uses_depth_pre_pass;
 
 	// actions.usage_flag_pointers["SSS_STRENGTH"] = &uses_sss;