The management layer has some old code that uses throwing or catching of NoSuchElementException as a way to represent that a resource doesn't exist. Clean this out so we can more easily move to a cleaner set of exceptions.

This work will consist of two aspects:

1) Code that's meant to catch Resource.NoSuchResourceException but instead catches its superclass NoSuchElementException will shift to catching the subclass. This will make the true intent of the code clearer.

2) The unused PathAddress.navigate and remove methods, which throw NoSuchElementException, will be deprecated. Using PathAddress to maneuver through a deep DMR node tree is not really how management works ever since we introduced the Resource class long long ago (hence these methods are unused.)