Fix formations not queueing orders properly.

Formation controllers were not always waiting on their members correctly because the "finishedOrder" check was being reset in the wrong place. This happened particularly with queued orders.

This merges the "finishedOrder" and the "InPosition" logic.

Reported by: elexis

Based on a patch by: Freagarach

Tested by: Freagarach

Reviewed By: Angen

Fixes #3274

Differential Revision: https://code.wildfiregames.com/D2702