List upcoming jobs

[borrob]

Is your feature request related to a problem? Please describe.

• To schedule new jobs for a new quality control, you might want to time it in such a way it doesn't coincide with a lot of other jobs.
• You might want an overview how many jobs you are running.
• Planning which failure notices you can skip in relation to planned maintenance/downtime.

Describe the solution you'd like A simple API and/or overview page that list all upcoming jobs.

Describe alternatives you've considered N.A.

Additional context Just an idea for a feature enhancement. Currently no practical usecase other than curiosity about upcoming jobs. It is related to #247 but shows upcomming/planned runs rather than finished runs.

Possible solution APScheduler can be configured to use a 'jobstore' (including SQLite) to store jobs (for GHCrunner). The GHCwebapp can access this information and show an overview page.