2D Motion Blur

## What problem does this solve or what need does it fill?

Motion blur has been implemented for 3D, would be great to have it for 2D as well :)

## What solution would you like?

Like the [3D example](https://github.com/bevyengine/bevy/blob/release-0.14.1/examples/3d/motion_blur.rs) but for 2D things.

## Additional context

Ideally, we should be able to do something like this and see motion blur:

```rust
use bevy::{
core_pipeline::motion_blur::{MotionBlur, MotionBlurBundle},
prelude::*,
};

fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup)
.add_systems(FixedUpdate, move_sprite)
.run();
}

fn setup(mut commands: Commands, asset_server: Res) {
commands.spawn((
Camera2dBundle::default(),
MotionBlurBundle {
motion_blur: MotionBlur {
shutter_angle: 1.0,
samples: 4,
},
..default()
},
));
commands.spawn(SpriteBundle {
texture: asset_server.load("branding/bevy_bird_dark.png"),
..default()
});
}

fn move_sprite(
time: Res,
mut query: Query<&mut Transform, With>,
mut move_left: Local,
) {
let mut transform = query.get_single_mut().unwrap();
if *move_left {
transform.translation.x -= 512.0 * time.delta_seconds();
if transform.translation.x < -100.0 {
*move_left = false;
}
} else {
transform.translation.x += 512.0 * time.delta_seconds();
if transform.translation.x > 100.0 {
*move_left = true;
}
}
}
```

Previous motion blur for 3D was submitted in this PR: https://github.com/bevyengine/bevy/pull/9924