Tracking Issue: Implement `DeviceEvent::ModifiersChanged`

[goddessfreya]

This issue tracks the implementation of DeviceEvent::ModifiersChanged that was discussed in #1124. PRs implementing this change should be made against the master branch.

• Public API changed
• Implemented on all platforms
  • Windows - Implement ModifiersChanged on Windows, and fix bugs discovered in implementation process #1344
  • macOS - Add ModifiersChanged event for macOS #1268
  • iOS
  • WASM
  • Linux X11 - Implement WindowEvent ModifiersChanged for X11 and Wayland #1132
  • Linux Wayland -Implement WindowEvent ModifiersChanged for X11 and Wayland #1132
• Added an entry to CHANGELOG.md if knowledge of this change could be valuable to users
• Updated feature matrix, if new features were added or implemented.

[goddessfreya]

Until it is implemented on all platforms, I've hidden ModifiersChanged. See #1152

[chrisduerr]

ModifiersChanged on macOS has been implemented in #1268.