CSGPolygon Add interpolation (Scaling/Moving) in mode Path

[stebulba]

This new feature from my proposal:
Add Scaling/Modify a CSG Polygon in PathFollow when PathNode is drawing the mesh
godotengine/godot-proposals#1062

• No conflict with anything else.
• No performance drop and no difference when is not active.
• path_joined is working with a manipulation of the path_curve.

I did't compile from the master. I had issues to compile Godot 4. But on 3.2.3.rc1 is running perfectly.

The interpolation work using a Curve who interpolate between two polygon array. If both polygons are equal, a single scaling mode is active.

If the path_polygon2 is empty, when you active the interpolation bool, you make a copy of the first polygon to the second. Is a way to reset or help you for editing the polygons.

Enjoy !

[stebulba]

I am re-writing the code to be compatible with the change #49313
90 % done and I will add more functionality / compatibility for all modes.

[stebulba]

Supersede by #53195
The cherrypick label can be remove.