Missing support for Kira Effects

[GitGhillie]

Kira Effects like reverb are a great way to quickly make your audio more immersive. I also have my WIP Steam Audio Rust rewrite implemented as a Kira Effect and it could work well together with bevy_kira_audio.

Kira Effects require you to use Kira Tracks, which is probably why it's not trivial to add support for this: While bevy_kira_audio does seem to have notion of tracks, it doesn't actually use Kira Tracks (except for the main track).