[ENHANCEMENT] expose Loaded filament material on the web-api

[schorsch3000]

Hi, i own a MK4 in an Original enclosure. I'm going to build an automatic fan controller for it. Depending in the printers status and the used fillament it will select a target temperature and controll the fan accordingly. It would be nuce if there would be an endpoint exposing the currently loaded filament type, currently i'll try to get these information from the jobs filename and the target bed temperature.