Add support for graph query languages

[bollwyvl]

Elevator Pitch

Add language server support for key graph query and data languages, such as SPARQL, Turtle, and GraphQL

Motivation

The most prominent language servers in this space just got a refresh, and it's probably worth trying them again.

Design Ideas

• Add specs for the stardog language server. Probably just the open standards (with or without quotes) mentioned above, rather than the stardog-specific languages.

• add at least ipython magic/syntax support for the unambiguous languages: %%sparql, %%graphql, %%ttl (but probably not turtle, which we don't want to trample).