Draft: Make manager help in setting up frame selection

Using a frame selection arbiter means, in addition to configuring the arbiter itself, adding configuration to the group matchers. Specifically:

• arbiter goes in sources list (sources)
• frame selection gets enabled (frameSelector.enable)
• arbiter gets set as frame selection source (frameSelector.arbiterSource)
• data source pattern is set up (frameSelector.dataSourcePattern)
• data keys to apply frame selection to must be configured (frameSelector.dataKeys)

And all of those things are annoying to do on multiple group matchers manually. Maybe we can make things a bit easier and thus encourage some use of frame selection.

Status: have added string so manager can know about unmanaged arbiter - like with geometry device. If an arbiter is specified, the group matchers are configured to use it.

To do:

• better default list of frameSelector.dataKeys
• discuss whether manager should manage arbiter
  • difficulty: it is a complicated device, relies on schema injection based on kernel(s) chosen
  • doubly so for the AdvancedFrameSelectionArbiter; the frame selection plan comes with more things to set up, some mandatory
  • difficulty: would need to rely heavily on restored configuration