Move "IsInRange" family of functions to the Obstruction Manager and make the commutative.
These functions were placed in UnitMotion, which had nothing to do with range checks and made them available only to moving entities for no particular reason.
This patch also adds support for square-square range checks and shape-shape distance checks.
Modified from a patch by bb on top of work from wraitii.
Differential Revision: https://code.wildfiregames.com/D981