This adds a new enum `KeyLocation` and associated property
`InputEventKey.location`, which indicates the left/right location of key
events which may come from one of two physical keys, eg. Shift, Ctrl.
It also adds simulation of missing Shift KEYUP events for Windows.
When multiple Shifts are held down at the same time, Windows natively
only sends a KEYUP for the last one to be released.
- Unify keycode values (secondary label printed on a key), remove unused hardcoded Latin-1 codes.
- Unify IME behaviour, add inline composition string display on Windows and X11.
- Add key_label (localized label printed on a key) value to the key events, and allow mapping actions to the unshifted Unicode events.
- Add support for physical keyboard (Bluetooth or Sidecar) handling on iOS.
- Add support for media key handling on macOS.
Co-authored-by: Raul Santos <raulsntos@gmail.com>
