API Move local solr to own repo

The local solr server was very out of date (because changing it would be an API change)
and took up lots of space in the repository.

This commit removes it, and references a newly created package,
silverstripe/fulltextsearch-localsolr

Not only does this save on storage space when the example server
isn't needed (you shouldn't really be using it for production), it
also disconnects the server version from the module version, so
you can easily change one without changing the other