Changing Box2D conversion factor reconfigures many joint anchors

[briansemrau]

When the conversion factor is changed in the project settings, many existing joints appear to be relocated across the screen. When the scene is saved and reloaded, custom configured anchors are still in the wrong position but default configured anchors return to the correct position.

[briansemrau]

Many joint node properties are tied to their respective b2Joint and b2JointDef, but by increasing their separation by duplicating the local anchors and storing them in Godot space the conversion factor should no longer be an issue.