UI - Add actions to check weapon zeroing when UI elements are disabled

[Drofseh]

When merged this pull request will:

• Add ACE interactions to check the zero of vehicle and unit weapons when their respective UI elements are disabled.
• Has a soft dependency on interaction (obviously) but I don't think this should be a problem as the action are added via config.
• The currentZeroing command is a little quirky, but I think it's still worth having despite these issues. It can't be used for a unit's primary/handgun weapon if the unit is in a vehicle. Return is for the vehicle weapon or [0,-1] depending on the syntax used. It doesn't work at all for FFV seats, even when firing the primary/handgun weapon. Return is 0 or [0,-1] depending on the syntax used. It doesn't currently work when the vehicle weapon zero is set using laser rangefinder. This should be fixed in Arma3 v2.20, but the current return is always the last manually set range.

[NikkoJT]

Biki says the alt syntax should work, but the return is always the last manually set range.

This is coming in the 2.20 update, which is expected in the next couple of weeks.