RCD airlock system upgrade + associated new proc

[Kubius]

Basically what the title says. Two part change:

• New airlock-fetcher proc that accepts optional access value and style parameters and returns the path of the appropriate airlock as compliant with map_setting. Originally created for a more elaborate project (which I may submit at a later time) but I realized it had general value and split it off into its own file.
  
• RCD retool to use the new fetcher proc. Basic RCDs can still only make basic airlocks, but they now follow the map style (and your direction as determined by player rotation), and construction RCDs have considerably more options available.
  

https://github.com/goonstation/goonstati...tchairlock

[warcrimes]

this is good QOL