[Repo creation] Atomatic repository content creation

[tusmester]

When the number of available repositories in snover gets too low, currently we only send a notification. We want to make repo content creation automatic.

• When there are too few available repositories, trigger a non-blocking background process that creates 5 more.
• properties are filled
  • content name is generated using the current algorithm
  • Status: Pending
  • other properties: host, id
• email notification is sent to the devops team