Auto explore order

**What do you want to see?**
An auto explore order which causes a ship to automatically explore the map by warping to the nearest unexplored system repeatedly.

**How would it help players?**
Reduce micromanagement of scout ships

**Alternatives**
N/A

**Screenshots and mockups**
N/A

**Things to consider**
This should not just issue a standard move/warp order because there could be another scout ship exploring that system in the mean time. Rather it should be its own order with its own pathfinding logic.