### Godot version

4.2 f7bc653

### System information

Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1060 (NVIDIA; 30.0.15.1403) - Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz (8 Threads)

### Issue description

`get_method()`:
```
Returns the name of the method represented by this Callable. If the callable is a lambda function, returns the function's name
```
However calling it on a named lambda results in
```
Can't get method on CallableCustom "test(lambda)".
```
(ironically the error even contains the function's name...)

`get_method()` in GDScriptLambdaCallable is likely unimplemented or is wrong. It should work for named lambdas.

### Steps to reproduce

```GDScript
var fun = func test(): pass
print(fun.get_method())
```

### Minimal reproduction project

N/A
#ifndef GDSCRIPT_LAMBDA_CALLABLE_H
#define GDSCRIPT_LAMBDA_CALLABLE_H
#include "core/object/ref_counted.h"
#include "core/templates/vector.h"
#include "core/variant/callable.h"
#include "core/variant/variant.h"
class GDScript;
class GDScriptFunction;
class GDScriptInstance;
class GDScriptLambdaCallable : public CallableCustom {
	GDScriptFunction *function = nullptr;
	Ref<GDScript> script;
	uint32_t h;
	Vector<Variant> captures;
	static bool compare_equal(const CallableCustom *p_a, const CallableCustom *p_b);
	static bool compare_less(const CallableCustom *p_a, const CallableCustom *p_b);
public:
	uint32_t hash() const override;
	String get_as_text() const override;
	CompareEqualFunc get_compare_equal_func() const override;
	CompareLessFunc get_compare_less_func() const override;
	ObjectID get_object() const override;
	void call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, Callable::CallError &r_call_error) const override;
	GDScriptLambdaCallable(Ref<GDScript> p_script, GDScriptFunction *p_function, const Vector<Variant> &p_captures);
	virtual ~GDScriptLambdaCallable() = default;
};
class GDScriptLambdaSelfCallable : public CallableCustom {