Monitoring schema cleanup

- Move 'monitoring.json' schema to sub folder 'data-types/monitoring'
- Changes indentation of the 'required' field in the monitoring schema, previously this was being listed as a property
- schemas lib now looks through the schemas folder rather than using a coded list 
Given that we reference data-sets in backdrop as `data-group/data-type`, what do you think about this description referring to it in the same way?