### 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
reference = p_self;
	object = p_self.ptr();
	function = p_function;
	captures = p_captures;
	h = (uint32_t)hash_murmur3_one_64((uint64_t)this);
}
GDScriptLambdaSelfCallable::GDScriptLambdaSelfCallable(Object *p_self, GDScriptFunction *p_function, const Vector<Variant> &p_captures) {
	object = p_self;
	function = p_function;
	captures = p_captures;
	h = (uint32_t)hash_murmur3_one_64((uint64_t)this);
}