Make GD singleton friendly to java

[CedNaru]

To make it possible I had to get rid of the code being split between different interfaces because it doesn't support @JvmStatic, necessary for Java to see them as static method.

Another alternative would be to create separate singleton GDPrint, GDMath, etc instead of them being interfaces.

[Copilot]

Pull Request Overview

This PR consolidates the GD singleton from interface-based architecture to a single object to enable Java interoperability through @JvmStatic annotations. The interfaces didn't support @JvmStatic annotations which are necessary for Java to access methods as static.

Key changes:

• Removed interface-based separation (GDMath, GDCore, GDRandom, GDPrint)
• Consolidated all functionality into the GD object with @JvmStatic annotations
• Made the RandomNumberGenerator instance private instead of part of an interface

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
GDRandom.kt	Removed interface, functionality moved to GD object
GDPrint.kt	Removed interface, functionality moved to GD object
GDMath.kt	Removed interface, functionality moved to GD object
GDCore.kt	Removed interface, functionality moved to GD object
GD.kt	Consolidated all functionality from interfaces with @JvmStatic annotations

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