Added filters to repeated orders

I hope https://github.com/OpenRA/OpenRA/issues/3923 addresses a lot of CPU and network performance problems when people click the same spot many times as seen by high APM *Craft players.

~~Note: there is still some leakage. You order a unit to attack, move somewhere, attack the same thing and it gets filtered. Not sure why. I added a lot of resets.~~ I simplified the implementation a lot and solved this on my own.
Hold shift, and then queue a movement path that includes duplicate waypoints.