To support the inactive project deletion feature we need to store the
following settings for the GitLab instance.
- Enable/disable inactive project deletion.
- Minimum size of the repository in MB that should be considered
for inactive project deletion.
- Time in months after which we need to send a warning email to the
project maintainers saying that their project will be deleted
because of inactivity.
- Time in months after which the project needs to be deleted
because of inactivity.

Changelog: added