### 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
#include "gdscript_rpc_callable.h"
#include "core/templates/hashfuncs.h"
#include "scene/main/node.h"
bool GDScriptRPCCallable::compare_equal(const CallableCustom *p_a, const CallableCustom *p_b) {
	return p_a->hash() == p_b->hash();
}
bool GDScriptRPCCallable::compare_less(const CallableCustom *p_a, const CallableCustom *p_b) {
	return p_a->hash() < p_b->hash();
}
uint32_t GDScriptRPCCallable::hash() const {
	return h;
}
String GDScriptRPCCallable::get_as_text() const {
	String class_name = object->get_class();
	Ref<Script> script = object->get_script();
	return class_name + "(" + script->get_path().get_file() + ")::" + String(method) + " (rpc)";
}
CallableCustom::CompareEqualFunc GDScriptRPCCallable::get_compare_equal_func() const {