Normalization anchor for sprite slice in dimensions of this slice (#12769)

# Objective

Fixes #12408 .
Fixes #12680.

## Solution

- Recaclulated anchor from dimensions of sprite to dimension of each
part of it (each part contains its own anchor)

Author: bugsweeper

crates/bevy_sprite/src/texture_slice/computed_slices.rs

@@ -53,10 +53,21 @@ impl ComputedTextureSlices {
                 flip_x,
                 flip_y,
                 image_handle_id: handle.id(),
-                anchor: sprite.anchor.as_vec(),
+                anchor: Self::redepend_anchor_from_sprite_to_slice(sprite, slice),
             }
         })
     }
+
+    fn redepend_anchor_from_sprite_to_slice(sprite: &Sprite, slice: &TextureSlice) -> Vec2 {
+        let sprite_size = sprite
+            .custom_size
+            .unwrap_or(sprite.rect.unwrap_or_default().size());
+        if sprite_size == Vec2::ZERO {
+            sprite.anchor.as_vec()
+        } else {
+            sprite.anchor.as_vec() * sprite_size / slice.draw_size
+        }
+    }
 }
 
 /// Generates sprite slices for a `sprite` given a `scale_mode`. The slices