Add support for Team Delays

[JoyfulShush]

Allows users to manage their map's TeamDelays key through WAE, which is something done somewhat common to control the production speed of the AI in many missions.

Introduces a new script. Running it opens the difficulty settings management window. For now, this only allows the user to instruct WAE to add a key for TeamDelays to the map, in which case they will have to provide values for each difficulty level:

Once applied, if the user saves, WAE will add [General] section if not exists yet, and will add the TeamDelays= key to it with the appropriate values. Likewise, if the user instructs WAE to not override team delays, WAE will remove TeamDelays= key from it, and also the [General] section if there are no other keys in it.

Supports loading and saving the values from and to any map being worked on.

[Rampastring]

I'm unsure whether this functionality actually belongs to WAE as difficulty settings are purely text-based and have no graphical impact. A script that adds all the difficulty code to the map for easy editing might already cut it together with the existing File -> Open With Text Editor.

That being said, if we go forward with this, the implementation needs some work.

Model-wise, TeamDelays does not belong into the Map, but to Rules. TeamDelays= exists in Rules.ini after all. It should also be of type int[] or List<int>, because TeamDelays= is a list of integers.

Then, modifying TeamDelays would change it in the Rules data instead of modifying the map model.

To save the modified Rules data, WAE would need a way to write specific rules overrides into the map when the map is saved. I don't think a function for this exists currently because WAE has no existing interface where you'd modify the values of Rules.ini keys.