Add endpoint to provide overview of job statuses

[gra-moore]

There is a need to understand which jobs may not have run or errored. We have a lot of this information but we can collect it together and make it easier for clients to understand the current job status.

This should include the last run and the next scheduled run. It would be useful to also understand if a job hasnt run according to schedule.

Add a /jobs/statuses endpoint that returns a summary of all jobs with key indicators.