AI meta data

Work done to make AI supportpower usage slightly smarter. Refer to #5830 

Allows some basic usage rules to be defined in yaml for supportpowers.
You need to update https://github.com/OpenRA/OpenRA/blob/bleed/OpenRA.Utility/Command.cs#L300 to first handle lists and also read nested ones. This is not trivial, so you may skip this for now (leave a `//TODO`) and just fix the comment here.

```diff
-For finding the general target area, before doing a detail scan.
+For doing a detailed scan in the general target area.
```