Propagate Parent Positions to children

[octotep]

It would be nice to allow parent entities to have a Postition that is then propagated to the children (and so on recursively). One could then easily group and move entities together, instead of separately.

[octotep]

Looks like there are some reworks to how bevy handles hierarchies in the pipeline, so I'm gonna wait until after that lands to tackle this. Should be pretty straightforward.