Add the "Danger Close" Radio Support distance to Missions Params

[LuizBarros99]

Is your feature request related to a problem? Please describe.
Something that I always found a little frustrating was that it is impossible to call in Radio Support (Air Strike or Fire Missions) close to either friendly players or even empty respawn positions.

And that is frequently frustrating when you are about to be overrun on a defensive position, which would allow to safely call danger close fire missions. It becomes frustrating because you will either be denied the fire support, or you will only be able to call it so far away from the target that it will not have any effect on target.

Describe the solution you'd like
Add a Radio Support "Danger Close Distance" parameter to the Mission Params settings. Basically same function as the "danger_distance" config value seen in the SOG PF Wiki article regarding the Radio Support module config.
One of the options should be the current "Danger Close Distance" value(s), and one other of them should be "Zero" (allow danger close, even on top of friendlies).

This would allow each server to EASILY select which Danger Close setting they like the most (if they suffer too much friendly fire, they can easily select a bigger distance setting. If they are unable to have effect on target, they can easily select a smaller distance setting)

Describe alternatives you've considered
The only alternative solution I can see would be for Server hosts to edit the Radio Support config file that contain the setting I described. But this probably would not be as easy and simple as changing Mission Params.