Port project to Godot 4.1.1

[daneehAI]

A complete port of Godot Steering AI Framework to Godot version 4.1.1

Brief summary of changes below

Automatic code changes:

• Godot auto-convert project from 3 to 4.1.1 to fix many syntax changes such as deg2rad() -> deg_to_rad()

Manual changes:

• Rename GSAIKinematicBody2DAgent and -3DAgent gdscripts to GSAICharacterBody2DAgent and -3DAgent to reflect namechange of the KinematicBody classes to CharacterBody classes in Godot 4
• Use new 'velocity' property from Godot 4 CharacterBody classes where applicable
• Update classes that use Referenced to instead use RefCounted, the Godot 4 name of that same class.
• Replace usage of deprecated FuncRef in favour of the new Callable class
• Update deprecated setget syntax to new get and set syntax
• Fix super calling to use new super keyword instead of deprecated '.' operator
• Replace yield keyword with new await keyword
• Update 'onready', 'export', 'export' with range, and 'tool' to new @ syntax
• Update update() to queue_redraw() for 2D drawers

Fix existing code to better fit GDQuest style guide:

• Move 'extends' to below 'class_name'

Notable demo scene changes:

• Application window scaling was broken for some 2D demo scenes. Add proper scaling code to func _ready() of those scenes
• Change position of some objects in 2D scenes to further fix broken window scaling

Update .gitignore for Godot 4 (ignore .godot/ instead of .imported/)

[NathanLovato]

Thanks much for this. Just so you know, I haven't forgotten about your contribution. We're just in crunch to release our new website and get everything in order for the 4.2 release.

I'll get to reviewing and testing this PR as soon as possible, but please note it may take another 2 weeks.

[NathanLovato]

I just got to this after nearly two months of crunch. Thanks for your patience and your contribution! It's working well and looking good. Time to merge!