feat: allow registration of systemwide tasks

[bomoko]

This PR introduces the ability to register system wide tasks.

These tasks will show up for particular environments just in case of the user having the appropriate permissions.

As part of the registration of a task, you will now need to set the 'systemWide' field to be equal to true in your API call, and specify no group, project, or environment.

General Checklist

• [ ] Affected Issues have been mentioned in the Closing issues section
• [ ] Documentation has been written/updated
• [ ] PR title is ready for inclusion in changelog

Database Migrations

• [ ] If your PR contains a database migation, it MUST be the latest in date order alphabetically

Explain the details for making this change. What existing problem does the pull request solve?

[shreddedbacon]

Once the tests pass :jenkins_dead: