ModelBuilder Canvas UI Scrolling/Panning Improvements (Pro)

[ColeAndrews]

The ModelBuilder canvas scroll bars, zooming, and panning is very restrictive, making for a clunky UX. Pro won't allow you to scroll/zoom/pan beyond the model tools. As we're building models, you have to add the tool on top of existing tools, then drag around the new tool to force the canvas to "expand". Allow the canvas to be user friendly, let users scroll/pan to where they want to work in the model. Don't require a tool to be drug around 'clunkily' to move to the proper spot on the canvas.