Improvements to selector tools #781

Ideas after meeting with @almarklein

• Infinite line in pygfx
• [ ] See if we can just use geo bbox for RectangleSelector
• [ ] Maybe draw these in an overlay render pass? Would allow 2D selector tools to be used in perspective projections. Rectangle selectors, polygon, circle etc. will have to scale w.r.t. the scene. Almar has now done this with render queues
• Polygon selector
• lasso selector
• allow setting a max range, Useful for LinearRegionSelector and any future resizable rectangle or polygon selectors. If they are tied to displaying a large sub-selection of data, it can be useful to prevent the selection from ever becoming too large.
• step size, useful for block based image algorithms and other use cases