[POC] Generate node types command

This is just a quick sketch of a command to generate CND files (just namespaces and names, no properties / children definitions).

In general binding document classes to node types will enable much more efficient filtering and selecting (e.g. `SELECT * FROM MyBundle:Article WHERE title = "foobar"`)

Obviously there is quite a large scope here, but just to follow on from *__what was the issue where we discussed this?__*

Next steps:

- [ ] Add configuration option to automatically assign node types to documents
- [ ] Provide node type migrate command (?)
the diff thing is not that important i think. removing is not possible anyways, so we can only add. and adding a nodetype that already exists is ok in cnd, its just a noop.