[WIP] Moving node validation from JL-Doctrine-DBAL to Jackalope

As suggested in the comments for this code in the doctrine-dbal implementation, this PR will aim to move the node validation to here.

The validate method currently also adds additional node operations (e.g. for node autocreate) to the transport, so I think it should probably be renamed / refactored.
Namespaces were lazy-loaded in the the `doctrine-dbal` implementation, i.e. they were only pulled in when a `NAME` property had to be validated. As this is a node save operation and its only a one-time call, I *think* its acceptable to not lazy load.