Autoscroll when mouse is outside viewport and dragging

[0HyperCube]

When moving an object with the select tool, it is useful to move the viewport if the mouse is outside of the viewport, similar to how it is done in inkscape.

https://github.com/GraphiteEditor/Graphite/assets/78500760/919b0719-0ce5-4e08-a414-958d43e57c84

[jafriyie1]

Hello, I would love to work on this if that is ok.

[Keavon]

Awesome, have at it! Once you open a draft PR, I'll assign you to this issue. Hop on our Discord if you need any help figuring things out :)

[Keavon]

@elbertronnie please reply "Ok" here so I can set you as this issue's Assignee. Thanks!

[elbertronnie]

@Keavon Ok