obs: add --allow-unknown-package

Prepare to add a wireshark package. It will be in its own
osmocom:wireshark repository, and not in osmocom:nightly, :latest,
:master, so it's not added to lib/config.py.

Move lib.set_args() before parse_packages(), so the latter is able to
use lib.args.allow_unknown_package.

Related: OS#2537
Change-Id: I007f937ccb629e0593ec9253541ed05df42fac66
2 files changed