Allow selectable component to overwrite shape of displayed selection from footprint

Removing strict binding of selection to footprint by adding optional choice similar in footprint. If present, that one will be used, else it will fallback to footprint size.
Allowing to use any selection shape without affecting gameplay, because foorprint is used for projectile hit detection.

Differential revision: https://code.wildfiregames.com/D2844
Reviewed by: wraitii