Allow users to provide image dimensions type/layers count in ImageLoaderSettings

[MatrixDev]

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

Makes the usage of stacked 2D array (and similar) textures much much easier and less error prone.

What solution would you like?

Adding enum specifying texture type during asset loading to ImageLoaderSettings:

enum ImageDimensions {
    D1,
    D2,
    D2Array(u32),
}

struct ImageLoaderSettings {
    // ...
    dimensions: ImageDimensions,
}

So it can be used after:

#[derive(Asset, AsBindGroup, Reflect, Debug, Default, Clone)]
struct MyMaterial {
    #[texture(0, dimension = "2d_array")]
    #[sampler(1)]
    pub textures: Handle<Image>,
}

let textures = assets.load_with_settings("assets/2d_array.png", |s: &mut ImageLoaderSettings| {
    s.dimentions = ImageDimensions::D2Array(3);
});

commands.spawn((
    Mesh3d(mesh),
    MeshMaterial3d(materials.add(MyMaterial { textures })),
));

What alternative(s) have you considered?

The only alternative so far is to track when the image was loaded and call reinterpret_stacked_2d_as_array manually. But this requires a lot of boiler plate code and feels like a workaround. Also if there is any delay in calling reinterpret_stacked_2d_as_array, program will crash because shader expects 2d-array texture, but receives 2d texture.