Provide API for inspecting the backend data

[robacarp]

Currently inspecting the backend data requires querying the backend directly. It would be nice to be able to ask mosquito's backend for data about:

• The current list of queues (Adds mosquito api for interacting with queues #153)
• The current list of job runs (Adds mosquito api for interacting with queues #153)
• A list of active runners overseers (Adds mosquito api for overseers #150)
• Statistics about a runner
  • How many tasks have been finished in the last hour,minute,second (Add a metric which tracks job runs per runner #156)
  • How many tasks have succeed or failed in the last (Add a metric which tracks job runs per runner #156)
• How many tasks have been enqueued in the last hour/minute/second (Add a metric which counts jobs enqueued #155)
• What a runner is currently doing (Adds mosquito api for Executors #147)
• JobRuns that have recently failed or succeeded
  • The parameters given to a job run (Adds mosquito api for Job Runs #148)
  • when it was started (Track more job run metadata #157)
  • how long it took to run (Track more job run metadata #157)

Prototyping for these features is being monkeypatched in the TUI Visualizer project.

[robacarp]

Closing in favor of milestone