Use 'faction' and 'gender' attributes to provide default values in MP Create.

Before this, 'faction' and 'gender' were not used if 'force_lock_settings'
wasn't set to 'yes'. This resulted in inconsistent behaviour between the
mentioned two attributes and 'type' attribute. When 'type' was set, the relevant
leader was always selected by default.

This partially fixes bugs #21753 and #20562. To properly address them, it might
be needed to add 'faction_lock', 'type_lock' and 'gender_lock' attributes so
that UMC authors would have a way to actually lock these selections without
using 'force_lock_settings' if they don't want to.