api: overhaul pointer API

- Rename `CursorMoved` to `PointerMoved`.
- Rename `CursorEntered` to `PointerEntered`.
- Rename `CursorLeft` to `PointerLeft`.
- Rename `MouseInput` to `PointerButton`.
- Add `position` to every `PointerEvent`.
- Remove `Touch`, which is folded into the `Pointer*` events.
- New `PointerType` added to `PointerEntered` and `PointerLeft`,
  signifying which pointer type is the source of this event.
- New `PointerSource` added to `PointerMoved`, similar to `PointerType`
  but holding additional data.
- New `ButtonSource` added to `PointerButton`, similar to `PointerType`
  but holding pointer type specific buttons. Use
  `ButtonSource::mouse_button()` to easily normalize any pointer button
  type to a generic mouse button.
- In the same spirit rename `DeviceEvent::MouseMotion` to `PointerMotion`.
- Remove `Force::Calibrated::altitude_angle`.

Fixes #3833.
Fixes #883.
Fixes #336.

Co-authored-by: Kirill Chibisov <contact@kchibisov.com>

examples/child_window.rs

@@ -44,7 +44,7 @@ fn main() -> Result<(), impl std::error::Error> {
                     self.windows.clear();
                     event_loop.exit();
                 },
-                WindowEvent::CursorEntered { device_id: _ } => {
+                WindowEvent::PointerEntered { device_id: _, .. } => {
                     // On x11, println when the cursor entered in a window even if the child window
                     // is created by some key inputs.
                     // the child windows are always placed at (0, 0) with size (200, 200) in the