### 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)


for (int i = 0; i < p_suite->statements.size(); i++) {
		GDScriptParser::Node *stmt = p_suite->statements[i];
		
		for (GDScriptParser::AnnotationNode *&E : stmt->annotations) {
			resolve_annotation(E);
			E->apply(parser, stmt);
		}
#ifdef DEBUG_ENABLED
		HashSet<GDScriptWarning::Code> previously_ignored_warnings = parser->ignored_warnings;
		for (GDScriptWarning::Code ignored_warning : stmt->ignored_warnings) {
			parser->ignored_warnings.insert(ignored_warning);
		}
#endif 
		resolve_node(stmt);
#ifdef DEBUG_ENABLED
		parser->ignored_warnings = previously_ignored_warnings;
#endif 
		decide_suite_type(p_suite, stmt);
	}
}
void GDScriptAnalyzer::resolve_assignable(GDScriptParser::AssignableNode *p_assignable, const char *p_kind) {
	GDScriptParser::DataType type;
	type.kind = GDScriptParser::DataType::VARIANT;
	bool is_constant = p_assignable->type == GDScriptParser::Node::CONSTANT;
	GDScriptParser::DataType specified_type;
	bool has_specified_type = p_assignable->datatype_specifier != nullptr;
	if (has_specified_type) {
		specified_type = type_from_metatype(resolve_datatype(p_assignable->datatype_specifier));
		type = specified_type;
	}