Access to ScriptServer

### Godot version

4.3 beta 2

### godot-cpp version

master

### System information

Windows 10 and Linux Mint

### Issue description

If implementing a module, we can include the `script_language.h` file then access `ScriptServer`. However this is not exposed to GDExtension. I don't know if there is a reason for that.

That said, there are a few things that are very useful. Of particular interest to me is querying if a scripted class inherits from a specific base. I know that we can manually do that by first obtaining the list of "global classes" (`ProjectSettings::get_singleton()->get_global_class_list()`. However this option means that we always have to iterate through the list of classes. Caching the data might result in outdated data. From my understanding `ScriptServer` is always updated whenever a scripted (global) class is created or removed.

I understand if not exposing `ScriptServer` is actually desired.

### Steps to reproduce

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### Minimal reproduction project

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