2d Bloom in the Bevy game engine

* GitHub: https://github.com/rust-adventure/bevy-examples/tree/418afebf3f411625e149a23c2a360ffeee71b2b7/examples/bloom-2d * boxes2: https://github.com/dimforge/bevy_rapier/blob/master/bevy_rapier2d/examples/boxes2.rs * BloomSettings: https://docs.rs/bevy/latest/bevy/core_pipeline/bloom/struct.BloomSettings.html