CI testing for the nextcloud package using the Test Management Tool (tmt)

### Tests

 - `occ` - tests basic functionality of the occ command
 - `cli-install` - tests if post-install/setup steps can be run via cli

### Plans

The plans directory contains template plans for this package. The actual plans run are contained in the [main nextcloud repo](https://src.fedoraproject.org/rpms/nextcloud).