virqemu: Don't strip the requested key from nested objects

virqemu: Don't strip the requested key from nested objects

Skipping of a specific key is needed only for the top level object to
specially handle the object type. We must not pass it to any recursed
printing of nested objects as skipping keys there might be surprising
and also is unhandlable later when formatting the commandline.

Until now this did not pose a problem but was discovered when adding a
new netdev backend which has a nested config object which also has the
'type' key which was being skipped.

Modern usage will prefer JSON directly but fix the commandline generator
to prevent surprises.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>