Batch loading multiple assets with naming patterns

[wentao]

There is the use case: I have a GLB file containing multiple animations named as

filename.glb#Animation{i}

where i starts with 0 and keeps incrementing. For example, if the glb file has 30 animations then in order to load them into a Vec, we have to do something like

#[derive(AssetCollection, Resource)]
pub struct Animations {
    #[asset(
        paths(
            "models/explosion.glb#Animation0",
            "models/explosion.glb#Animation1",
            "models/explosion.glb#Animation2",
            "models/explosion.glb#Animation3",
            "models/explosion.glb#Animation4",
            "models/explosion.glb#Animation5",
            "models/explosion.glb#Animation6",
            "models/explosion.glb#Animation7",
            "models/explosion.glb#Animation8",
            "models/explosion.glb#Animation9",
            "models/explosion.glb#Animation10",
            "models/explosion.glb#Animation11",
            "models/explosion.glb#Animation12",
            "models/explosion.glb#Animation13",
            "models/explosion.glb#Animation14",
            "models/explosion.glb#Animation15",
            "models/explosion.glb#Animation16",
            "models/explosion.glb#Animation17",
            "models/explosion.glb#Animation18",
            "models/explosion.glb#Animation19",
            "models/explosion.glb#Animation20",
            "models/explosion.glb#Animation21",
            "models/explosion.glb#Animation22",
            "models/explosion.glb#Animation23",
            "models/explosion.glb#Animation24",
            "models/explosion.glb#Animation25",
            "models/explosion.glb#Animation26",
            "models/explosion.glb#Animation27",
            "models/explosion.glb#Animation28",
            "models/explosion.glb#Animation29",
        ),
        collection(typed)
    )]
    pub explosion: Vec<Handle<AnimationClip>>,
}

This works, but it's very tedious and error prone to manually constructs the paths array.

It would be great if we can add some path_pattern support. Maybe something like the following

[asset(paths_pattern("filename.glb#Animation{}", 0..30), collection(typed)]