[SoftwareUpdater] try full-sync if haiku package is missing from update

[diver]

hrev54083 x86_64

Currently, SoftwareUpdater uses the same logic as pkgman update - i.e. it will not try to uninstall existing packages. However, from time to time some packages become obsolete and they are required to be uninstalled like what happened recently with ilmbase. This led to a situation where haiku package couldn't be updated and unsuspecting users don't understand why SoftwareUpdater stopped updating packages.

If possible SoftwareUpdater should detect this situation (when there is an update for haiku_loader package but not for haiku) and offer retrying in full-sync mode.

pkgman update could also at least warn the user about this situation.