Feature Request: Provide utility functions for converting between path formats

[jcmcken]

I think it would be useful to promote the _path_join function to a public function (path_join) and have the reverse function also available (path_split?).

In my use case, I need to check certain things about keys within the path itself, so I need to re-split the JSON patch path (convert it from a string to a tuple). Having to reverse-engineer the _path_join function in my own code is not hard, but I would prefer if the library that's creating that path in the first place also has a way to reverse it if I want to convert in the opposite direction.