simpleran: use jsonschemas

• Use jsonschemas recipe
• Fix all wrong usages of $refs in json files
• Support ORS Brute (currently manual patch is needed)
• Publish configuration file in monitor folder: some clients want to see all RAN parameters
• Define state of requested instances: to try to prevent monitor instance stuck in stop requested state
• Fix not being able to update ssb_nr_arfcn for ORS
• Fix core network buildout crashing when no websocket frontend is there yet
• Use new slapos toolbox for GPS promise: https://lab.nexedi.com/nexedi/slapos.toolbox/-/merge_requests/156
• Add Core Network Local DNS Entry to JSON Schema

/cc @tomo @xavier_thompson