core: ping: refactor to be a BlueOS Extension

I've brought this up previously, but just formalising some thoughts on the matter here:

Now that the BlueOS Extensions system is in place it makes sense to pull the Ping Sonar Devices integration functionality out of core BlueOS and into an Extension, so that
1. it can be maintained independently of BlueOS (with more targeted feature/development tracking)
2. it avoids showing unnecessary favouritism to Blue Robotics components
3. it can be uninstalled/disabled by users who don't need the functionality (to save resources and visual clutter)
4. it can be used as a test-bed of our Extensions system processes, and help to find missing/sub-par documentation and other potential pain points for external integrators
5. the functionality can be more readily expanded without worrying about cramming unnecessary stuff into BlueOS core (e.g. for things like [device firmware flashing](https://github.com/bluerobotics/BlueOS/issues/264#issuecomment-1058696867))

If we still want it available to new users by default then we can make it a default installed extension (once the mechanisms are in place for that kind of functionality).