Port Dynamic Tilemap Layers 2D demo to C# Godot mono 4.2

[DevDaddyDownUnder]

This change ports the Dynamic Tilemap Layers 2D demo to C#.

Version: Godot mono 4.2

[Calinou]

Thanks for opening a pull request!

As per the contribution guidelines, we should consider whether a C# port of this demo is really justified. We try to keep C# ports to a minimum, as they tend to get out of sync compared to their GDScript counterpart over time. To me, the demo's logic seems relatively simple and doesn't feature too many things that would vary between GDScript and C#.

C#-specific demos are most suited for features that look very different between GDScript and C#, e.g. editor plugins.