Cleanup bevy winit (bevyengine#11489)

# Objective

Get bevyengine#11257 changes merged.

I rewrote them one by one checking each to ensure correctness. In
particular, the window rescale logic changes to accomodate mut app
access are double checked. Not all changes have been included as some of
bevy_winit has since changed, and i am not confident including them.
Namely, the `run_app_update_if_should` change.

### Notes to reviewers

Review commits individually, use the "Hide whitespaces" diff display
mode.

## Changelog

* `bevy::window::WindowMoved`'s `entity` field has been renamed to
`window`


## Migration Guide

`bevy::window::WindowMoved`'s `entity` field has been renamed to
`window`. This is to be more consistent with other windowing events.

Consider changing usage:

```diff
-window_moved.entity
+window_moved.window
```

---------

Co-authored-by: François <mockersf@gmail.com>

crates/bevy_window/src/event.rs

@@ -332,7 +332,7 @@ pub enum FileDragAndDrop {
 )]
 pub struct WindowMoved {
     /// Window that moved.
-    pub entity: Entity,
+    pub window: Entity,
     /// Where the window moved to in physical pixels.
     pub position: IVec2,
 }