User callback should fully resolve across interfaces

[stonier]

Should fully resolve a serviceResolved callback across all interfaces.

Currently this will only provide a ros service info with information from the one interface which triggered it. It would be good to check the other interfaces and bring all the information together, and pass that.

When an interface is dropped, that might also be a good place to trigger serviceResolved and serviceRemoved callbacks from the user - but to differentiate we need to check if it is still being served on the other interfaces first.