Issue #2244513 by kim.pepper, phenaproxima, 20th, andrei.dincu, beejeebus, Berdir, alexpott, jibran, andypost, larowlan, Chadwick Wood, acbramley, Wim Leers, sun, xjm, YesCT, chx, tim.plunkett: Move the unmanaged file APIs to the file_system service (file.inc)