Yeet away current DefaultInputPlugin implementation and replace it with proper one

Sub-issue of #19741 Upstreamed version of ``DefaultInputPlugin`` inside ``PanOrbitCamera`` is not sufficient for future Bevy Editor's use cases. ## Current version of collective proposal - [ ] Move current version of ``DefaultInputPlugin`` into examples folder as example how to replace input plugin for ``PanOrbitCamera``. - [ ] Implement new version of ``DefaultInputPlugin`` based on window-picking Drag observers ## Additional context Further discussions are welcome in [#editor-dev](https://discord.com/channels/691052431525675048/789987800014651412)