fix: Bepu and InputSystem update order

[Eideren]

PR Details

Set the update order for the InputSystem to a non-zero value, it will now always run before other systems with unset order.
Previously, users may inadvertently introduce a one-frame input latency to their scripts by creating the ScriptSystem before the InputSystem.
Also provides a way for users to insert systems that may run after the InputSystem but before the ScriptSystem without touching those two systems or creating a custom game implementation.

Given the above, moved the execution point of Bepu earlier in the frame, before ScriptSystem runs to make sure interpolated bodies update their positions before users may read them in update, but after InputSystem otherwise users would be reading last frame's input when they implement Components.ISimulationUpdate.

The above will reduce/eliminate apparent stuttering with user script when moving objects based on physics object transforms.

Related Issue

None afaict.

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My change requires a change to the documentation.
• I have added tests to cover my changes.
• All new and existing tests passed.
• I have built and run the editor to try this change out.

[Doprez]

LGTM

On a side note, would it make sense to create a PR tag for minor behaviour changes in code? I don't see this breaking anything but adding this with a specific note to releases may help existing users who may have done something specific with GameSystem order.

[Eideren]

@Doprez Good idea, added Behavioral-Change