Added process_physics_priority settings for Godot 4.1+

[Malcolmnixon]

This pull request adds the process_physics_priority settings to objects needing custom physics order. The settings are required for Godot 4.1+, but are ignored for Godot 4.0 which uses the process_priority setting for both render and physics.

[BastiaanOlij]

Cool, so we'll need to be careful that we don't accidentally undo these as opening up the project in Godot 4.0.3 will eventually clear them out when it decides to (re)save these scenes.