Add Non-Hostile UPP ERT

[Steelpoint]

About the pull request

Adds a non-hostile UPP ERT alternative to the hostile ERT spawn. Has the same chance to spawn as the hostile version.

Explain why it's good for the game

In lore the UPP enjoy a cold war esque relationship with the UA, a possibly neutral ERT helps better reflect this.

Furthermore, as more UPP are added to the game, the need to help shift the community meta regarding UPP away from 100% hostile to 50/50 hostile is going to become more important, this would be 1 small step.

Testing Photographs and Procedure

Screenshots & Videos

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Changelog

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add: UPP ERT's have a chance to be neutral to the USCM.
/:cl:

[JackieEstegado]

You may want to put in an exclusivity check so that a (non admin) UPP ERT of the oppossing friendliness cant spawn if one was spawned earlier (ie by an admin)

[fira]

Funny. A global toggle to ensure consistency might be cool but that means having to hack into ERT code

[Skatuk]

USCM and UPP are in a hostile situation. If USCM were to get damaged, the UPP would start a war and end them whenever they can. I don't see a reason why they'd want to help eachother when they both want eachothers death. Lore wise they also had the largest conflict between eachother, operation canton being the example. Sorry, but its a no from me.