### Godot version

4.1.beta3

### System information

Fedora Workstation 38 - Godot 4.1.beta3 - Vulkan (Forward+)

### Issue description

**This is an issue created by the production team, we're working on it**

Currently, it's impossible to call virtual functions within GDScript.

This currently returns an error:
```gdscript
# a.gd
extends Node

func _process(delta: float) -> void:
	pass
```

```gdscript
# main.gd
extends Node

var my_node: Node = preload("res://a.gd").new()

func _process(delta: float) -> void:
	my_node._process(delta)  # Cannot call virtual function "_process()" because it hasn't been defined.
```

### Steps to reproduce

1. Create a script (`a.gd`) based on `Node` that declares `_process()`;
2. Create a main node;
3. Attach a script to the main node;
4. Initialize a variable with a new `a.gd` instance;
5. Try to run `_process()` on that node;
6. Find out that it returns an error.

### Minimal reproduction project

[virtual_functions.zip (updated)](https://github.com/godotengine/godot/files/11823992/virtual_functions.zip)


static constexpr const char *kind = "constant";
	resolve_assignable(p_constant, kind);
#ifdef DEBUG_ENABLED
	if (p_is_local) {
		if (p_constant->usages == 0) {
			parser->push_warning(p_constant, GDScriptWarning::UNUSED_LOCAL_CONSTANT, p_constant->identifier->name);
		}
		is_shadowing(p_constant->identifier, kind);
	}
#endif
}
void GDScriptAnalyzer::resolve_parameter(GDScriptParser::ParameterNode *p_parameter) {
	static constexpr const char *kind = "parameter";
	resolve_assignable(p_parameter, kind);
}
void GDScriptAnalyzer::resolve_if(GDScriptParser::IfNode *p_if) {
	reduce_expression(p_if->condition);
	resolve_suite(p_if->true_block);
	p_if->set_datatype(p_if->true_block->get_datatype());
	if (p_if->false_block != nullptr) {
		resolve_suite(p_if->false_block);
		decide_suite_type(p_if, p_if->false_block);
	}
}
void GDScriptAnalyzer::resolve_for(GDScriptParser::ForNode *p_for) {