exposing chmod / attrib, ignore missing keys

[Leerz]

would this be available in the future versions? some basic fileops will file to copy/delete/move if they are marked readonly
it's implemented in fs but not in scripts if i understand right

source/libs/fatfs/ffconf.h

we get error #7 line 175 in the fscopy.c

i know that's exactly the purpose of that tag but we could override it similarly with
#require minerva
#override attrib

another note is that perhaps there's a tag to just ignore if keys are absent, basic file-ops don't really need prod.keys
absence if #require keys still asks for keys.