* Fix pkg_mgr fact on OpenBSD
Add a OpenBSDPkgMgrFactCollector that hardcodes pkg_mgr
to 'openbsd_pkg'. The ansible collector will choose the
OpenBSD collector if the system is OpenBSD and the 'Generic'
one otherwise.
This removes PkgMgrFactCollectors depenency on the
'system' fact being in collected_facts, which also
avoids ordering issues (if the pkg mgr fact is collected
before the system fact...)
Fixes#30623