feat: add utility function for adding info for new entities

[LordMidas]

No description provided.

[Darxo]

I suggest a second function that accepts an array of EntityInfo.
That will make adding a dozen entities at a time look cleaner in the code of mods

[LordMidas]

Upon gaining more experience with adding new entities, I have gained more insight that leads to me to think that this PR is not enough. Namely EntityType is only a thing to count entities and get their names in vanilla. So we need to handle them separately from Troops which are actual units that spawn on the map. So I'll think more on this PR and come up with better solutions.

[Enduriel]

In that case let's postpone