Add support for making the solr schema from a single class within schema

[kevinschaper]

• Add support for limiting the solr schema to a "top class"
• Update linkml

[glass-ships]

@kevinschaper out of curiosity, any progress on this?
would be nice to eventually point to a version of linkml-solr instead of a branch

[kevinschaper]

Let's re-run tests and see if we just need to remove 3.7.

[kevinschaper]

Now I'm remembering that these tests have never worked, because they expect a running Solr.