Attribute modifiers (Production time & Income)

Meant to close #6103.

This functional (but sickly) PR allows you to select production time and income modifiers per player in the lobby.

But the chrome work I did for it is an **ugly abomination**, and I need input into what would be the best way to lay it out and display it.

It is, however, somewhat functional. Classic production queues work for all mods, and income modifiers work for all mods.

But C&C:TD style production queues do not currently seem to like fetching the production time modifier from the player actor. Busy looking into this.

I did do a "multiplayer" test between two clients on my machine and did not get any desyncs, so that at least is a good start.
Skirmish tests also worked fine.