Lucene linguistics config builder

[dainiusjocas]

Maybe pyVespa could include a less verbose lucene linguistings config builder?

The default XML and VT implementation is more verbose than it should be.

A more concise API for example can be found here.

[thomasht86]

It would be nice, but since this is a new feature, I think we won't introduce a more ergonomic config builder until we know a bit more about the usage. And also suggest we create some vt-based examples first.