Files passed as arguments: Ignore unsupported files

With this patch, Dolphin ignores all files passed to it that it can't

Also, archives are now opened inside Dolphin so it can be used as an
archive manager at least for local files. If the user tries to open a
remote archive Dolphin still opens it externally; I have observed that
if it receives one as an argument, it will display a pseudo-folder that
contains only said archive. So having it set as the archive handler is
still broken, but in a less annoying way.

CCBUG: 318683
REVIEW: 113191
FIXED-IN: 4.11.3