Make sprite picking opt-in (#17842)

# Objective

Fix https://github.com/bevyengine/bevy/issues/17108
See
https://github.com/bevyengine/bevy/issues/17108#issuecomment-2653020889

## Solution

- Make the query match `&Pickable` instead `Option<&Pickable>`

## Testing

- Run the `sprite_picking` example and everything still work


## Migration Guide

- Sprite picking are now opt-in, make sure you insert `Pickable`
component when using sprite picking.
```diff
-commands.spawn(Sprite { .. } );
+commands.spawn((Sprite { .. }, Pickable::default());
```

crates/bevy_sprite/src/picking_backend.rs

@@ -42,7 +42,7 @@ pub enum SpritePickingMode {
 #[reflect(Resource, Default)]
 pub struct SpritePickingSettings {
     /// When set to `true` sprite picking will only consider cameras marked with
-    /// [`SpritePickingCamera`] and entities marked with [`Pickable`]. `false` by default.
+    /// [`SpritePickingCamera`].
     ///
     /// This setting is provided to give you fine-grained control over which cameras and entities
     /// should be used by the sprite picking backend at runtime.
@@ -94,7 +94,7 @@ fn sprite_picking(
         Entity,
         &Sprite,
         &GlobalTransform,
-        Option<&Pickable>,
+        &Pickable,
         &ViewVisibility,
     )>,
     mut output: EventWriter<PointerHits>,
@@ -102,8 +102,7 @@ fn sprite_picking(
     let mut sorted_sprites: Vec<_> = sprite_query
         .iter()
         .filter_map(|(entity, sprite, transform, pickable, vis)| {
-            let marker_requirement = !settings.require_markers || pickable.is_some();
-            if !transform.affine().is_nan() && vis.get() && marker_requirement {
+            if !transform.affine().is_nan() && vis.get() {
                 Some((entity, sprite, transform, pickable))
             } else {
                 None
@@ -219,8 +218,7 @@ fn sprite_picking(
                     }
                 };
 
-                blocked = cursor_in_valid_pixels_of_sprite
-                    && pickable.is_none_or(|p| p.should_block_lower);
+                blocked = cursor_in_valid_pixels_of_sprite && pickable.should_block_lower;
 
                 cursor_in_valid_pixels_of_sprite.then(|| {
                     let hit_pos_world =

examples/picking/sprite_picking.rs

@@ -60,6 +60,7 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
                     .spawn((
                         Sprite::from_color(Color::BLACK, sprite_size),
                         Transform::from_xyz(i * len - len, j * len - len, -1.0),
+                        Pickable::default(),
                     ))
                     .observe(recolor_on::<Pointer<Over>>(Color::srgb(0.0, 1.0, 1.0)))
                     .observe(recolor_on::<Pointer<Out>>(Color::BLACK))
@@ -79,6 +80,7 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
                         Transform::from_xyz(i * len - len, j * len - len, 0.0)
                             .with_scale(Vec3::splat(1.0 + (i - 1.0) * 0.2))
                             .with_rotation(Quat::from_rotation_z((j - 1.0) * 0.2)),
+                        Pickable::default(),
                     ))
                     .observe(recolor_on::<Pointer<Over>>(Color::srgb(0.0, 1.0, 0.0)))
                     .observe(recolor_on::<Pointer<Out>>(Color::srgb(1.0, 0.0, 0.0)))
@@ -140,6 +142,7 @@ fn setup_atlas(
             Transform::from_xyz(300.0, 0.0, 0.0).with_scale(Vec3::splat(6.0)),
             animation_indices,
             AnimationTimer(Timer::from_seconds(0.1, TimerMode::Repeating)),
+            Pickable::default(),
         ))
         .observe(recolor_on::<Pointer<Over>>(Color::srgb(0.0, 1.0, 1.0)))
         .observe(recolor_on::<Pointer<Out>>(Color::srgb(1.0, 1.0, 1.0)))