New: F3 assignGear AI component

* Automatically equips AI infantry with F3 gear, based on their classname
* Runs only after mission start and with short sleep between units to avoid heavy performance impact (could still be noticeable in missions with hundreds of AI)
* Class -> F3 gear type assignment via paired array in scriptfile
* Can be passed an array of units to process, by default processes all AI present (excl. playableUnits)
* To ignore AI set variable ["f_var_assignGear_done", false]; in unit init
* Calling assignGear via unit init always has precedence over assignGear AI script
* Thanks to PabstMirror for the idea and his work which this is based on