Stylus and touch support on windows

Right now only the mouse can be controlled, things like pressure or touch events are not handled. I do not run windows myself and thus will most likely not implement this, but if someone else is up to the task here is what needs to be done:

Implement the InputDevice trait: https://github.com/H-M-H/Weylus/blob/master/src/input/device.rs, send_event is called on every PointerEvent sent from the browser. The PointerEvent type is defined in https://github.com/H-M-H/Weylus/blob/master/src/protocol.rs. x and y coordinates of the events are normalized to a range between 0 and 1, have a look at https://github.com/H-M-H/Weylus/blob/master/ts/lib.ts.

Once a struct that implements this trait is done (should be in its own file in https://github.com/H-M-H/Weylus/blob/master/src/input/), it has to be instantiated in https://github.com/H-M-H/Weylus/blob/master/src/websocket.rs setup.

Probably useful:

• https://github.com/microsoft/winrt-rs
• https://github.com/retep998/winapi-rs
• https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-injecttouchinput