Create dynamic query/system example.

[rj00a]

Similar to https://github.com/bevyengine/bevy/blob/main/examples/ecs/dynamic.rs

[AsterixxxGallier]

I attempted to work on this issue, but evenio seems to not support dynamically inserting components into entities as of yet. The bevy example seems to rely on EntityWorldMut::insert_by_ids (that takes a bundle; insert_by_id is the single-component version and would also work). I couldn't find an equivalent function for inserting dynamic components in evenio. I assume this needs to be implemented first, before such an example can be written?