SS Registration verified: Create network invoice

Sometimes people don't have Internet because they have not done a social service. If you verify the social service they have done no new network invoice is created and they have to wait until the cron job that creates the invoices runs again (currently ever our). This is bad if you write an email like "I have verified the social service, you should have internet again". So to fix this problem the code now directly creates a new network invoice if a social service is verified.

cc @timothy-at-hilton Glaube das braucht keine Review, aber tagge dich trotzdem mal