Engine Upgrade (Godot 4.7) and DrawableTexture2D Implementation

[jordanbrotherton]

Godot 4.7 introduces a new node, DrawableTexture2D, which seems to be useful for Sketchpad. Right now it is purely observational, since the node appears to have an experimental, unstable API along with the refactor needed to implement it.

Benefits:

• A direct blit_rect function which seems to simplify a lot of drawing functionality from needing to convert into an image to purely modifying textures.
• This would greatly reduce code complexity and improve performance.

Concerns:

• The class page has a warning on almost all of the core functions: "Experimental: This method may be changed or removed in future versions."
• There seems to be quite a few concerns with instability judging from reports from the beta releases.

Further research and testing would be needed, but it could lead to a great improvement.