Using KKnD research logic for upgrades

[MustaphaTR]

Logic used by KKnD mod researches should easily allow us to implement building upgrades properly on D2, only difference from original D2 is being you click a UI button, then a building (which is the case for repairing too). Rather than selecting a building first and than clicking an upgrade button. Would also allow us to fill the empty space that removing sell button created (not that it matters much, we'll eventually replace the UI).

[MustaphaTR]

I looked into the code a bit this is gonna require us to update the mod to lastest playtest, KKnD is using https://github.com/OpenRA/OpenRA/commit/4e8eab4ca00d1910203c8a103dfd2c002714daa8 as engine version and we are missing a lot that is required for that logics.