Reimplement Resource._local_to_scene_setup & remove workaround

Reimplements the virtual method _setup_local_to_scene, lost in #51970, and renames it to `_local_to_scene_setup`.

Also deprecates the redundant `setup_local_to_scene_requested` signal.

core/io/resource.cpp

@@ -379,8 +379,8 @@ Node *Resource::get_local_scene() const {
 }
 
 void Resource::setup_local_to_scene() {
-	// Can't use GDVIRTUAL in Resource, so this will have to be done with a signal
 	emit_signal(SNAME("setup_local_to_scene_requested"));
+	GDVIRTUAL_CALL(_local_to_scene_setup);
 }
 
 void Resource::reset_local_to_scene() {
@@ -458,8 +458,9 @@ void Resource::_bind_methods() {
 
 	MethodInfo get_rid_bind("_get_rid");
 	get_rid_bind.return_val.type = Variant::RID;
-
 	::ClassDB::add_virtual_method(get_class_static(), get_rid_bind, true, Vector<String>(), true);
+
+	GDVIRTUAL_BIND(_local_to_scene_setup);
 }
 
 Resource::Resource() :

core/io/resource.h

@@ -33,6 +33,7 @@
 
 #include "core/io/resource_uid.h"
 #include "core/object/class_db.h"
+#include "core/object/gdvirtual.gen.inc"
 #include "core/object/ref_counted.h"
 #include "core/templates/safe_refcount.h"
 #include "core/templates/self_list.h"
@@ -81,6 +82,7 @@ class Resource : public RefCounted {
 	void _take_over_path(const String &p_path);
 
 	virtual void reset_local_to_scene();
+	GDVIRTUAL0(_local_to_scene_setup);
 
 public:
 	static Node *(*_get_local_scene_func)(); //used by editor

doc/classes/Resource.xml

@@ -19,6 +19,21 @@
 				Override this method to return a custom [RID] when [method get_rid] is called.
 			</description>
 		</method>
+		<method name="_local_to_scene_setup" qualifiers="virtual">
+			<return type="void" />
+			<description>
+				Override this method to customise the newly duplicated Resource created from [method PackedScene.instantiate], if the original's [member resource_local_to_scene] is set to [code]true[/code].
+				[b]Example:[/b] Assign a random value to [code]health[/code] for every duplicated Resource from an instantiated scene, excluding the original.
+				[codeblock]
+				extends Resource
+
+				var health = 0
+
+				func _local_to_scene_setup():
+				    health = randi_range(10, 40)
+				[/codeblock]
+			</description>
+		</method>
 		<method name="duplicate" qualifiers="const">
 			<return type="Resource" />
 			<param index="0" name="subresources" type="bool" default="false" />
@@ -58,20 +73,8 @@
 		<method name="setup_local_to_scene">
 			<return type="void" />
 			<description>
-				Emits the [signal setup_local_to_scene_requested] signal. If [member resource_local_to_scene] is set to [code]true[/code], this method is called from [method PackedScene.instantiate] by the newly duplicated resource within the scene instance.
-				For most resources, this method performs no logic of its own. Custom behavior can be defined by connecting [signal setup_local_to_scene_requested] from a script, [b]not[/b] by overriding this method.
-				[b]Example:[/b] Assign a random value to [code]health[/code] for every duplicated Resource from an instantiated scene, excluding the original.
-				[codeblock]
-				extends Resource
-
-				var health = 0
-
-				func _init():
-				    setup_local_to_scene_requested.connect(randomize_health)
-
-				func randomize_health():
-				    health = randi_range(10, 40)
-				[/codeblock]
+				Calls [method _local_to_scene_setup]. If [member resource_local_to_scene] is set to [code]true[/code], this method is called from [method PackedScene.instantiate] by the newly duplicated resource within the scene instance.
+				For most resources, this method performs no logic of its own. Custom behavior can be defined by overriding [method _local_to_scene_setup] in a script, [b]not[/b] by overriding this method.
 			</description>
 		</method>
 		<method name="take_over_path">
@@ -102,10 +105,5 @@
 				[b]Note:[/b] This signal is not emitted automatically for properties of custom resources. If necessary, a setter needs to be created to emit the signal.
 			</description>
 		</signal>
-		<signal name="setup_local_to_scene_requested">
-			<description>
-				Emitted when [method setup_local_to_scene] is called, usually by a newly duplicated resource with [member resource_local_to_scene] set to [code]true[/code]. Custom behavior can be defined by connecting this signal.
-			</description>
-		</signal>
 	</signals>
 </class>

editor/renames_map_3_to_4.cpp

@@ -213,6 +213,7 @@ const char *RenamesMap3To4::gdscript_function_renames[][2] = {
 	{ "_get_configuration_warning", "_get_configuration_warnings" }, // Node
 	{ "_set_current", "set_current" }, // Camera2D
 	{ "_set_editor_description", "set_editor_description" }, // Node
+	{ "_setup_local_to_scene", "_local_to_scene_setup" }, // Resource
 	{ "_toplevel_raise_self", "_top_level_raise_self" }, // CanvasItem
 	{ "_update_wrap_at", "_update_wrap_at_column" }, // TextEdit
 	{ "add_animation", "add_animation_library" }, // AnimationPlayer
@@ -642,6 +643,7 @@ const char *RenamesMap3To4::csharp_function_renames[][2] = {
 	{ "_SetCurrent", "SetCurrent" }, // Camera2D
 	{ "_SetEditorDescription", "SetEditorDescription" }, // Node
 	{ "_SetPlaying", "SetPlaying" }, // AnimatedSprite3D
+	{ "_SetupLocalToScene", "_LocalToSceneSetup" }, // Resource
 	{ "_ToplevelRaiseSelf", "_TopLevelRaiseSelf" }, // CanvasItem
 	{ "_UpdateWrapAt", "_UpdateWrapAtColumn" }, // TextEdit
 	{ "AddAnimation", "AddAnimationLibrary" }, // AnimationPlayer