ade: Correct order of deprecated passthrough arguments

When unparsed arguments were picked out, they were appended
to args. This is problematic if the wrapped command takes
command-line options with values of the form "--foo bar" (as
opposed to --foo=bar), because they would be re-ordered to "bar --foo",
likely causing a syntax error. It is obviously also a problem if
order is significant for the wrapped command. Prepend the unparsed
arguments to args instead of appending.

Signed-off-by: Simon McVittie <smcv@collabora.com>
Reviewed-by: André Magalhães <andre.magalhaes@collabora.co.uk>
Differential Revision: https://phabricator.apertis.org/D6798