Add an option to emulate macOS trackpad input behaviour on linux

On linux, you need to press the middle mouse button to orbit. There is an input setting that allows trackpad users to emulate a middle mouse click with the alt/meta key, however this action still requires the user to click and drag to rotate the view. Holding down shift switches the behaviour to panning instead. To zoom in/out you need to scroll vertically, which is slightly counter-intuitive on a trackpad.

On macOS, you can orbit the view with a 2 finger swipe. You don't need to click/press anything down. Holding down shift switches the behaviour to panning instead. Because scrolling vertically pans the camera vertically, you zoom in/out by pinching in/out 2 fingers. This action also doesn't require the user to click on the trackpad or press any keys.

On linux, Firefox (and presumably Chrome) behaves closer to the macOS version of blender: 2 finger pinch zooms in/out the view, and 2 finger swiping scrolls/pans the screen.

Adding an input setting on linux to emulate macOS trackpad behaviour (by having 2 finger swipes be interpreted as a middle click drag and 2 finger pinch be interpreted as vertical scrolling, if not by directly calling those actions) would be greatly appreciated.