Missing server implementations

[timbl]

We have a listing of Solid server products which is out of date, and needs to add a list of commercial products.

On the open source side, not 100% working, there is Henry's Scala project
https://forum.solidproject.org/t/new-scala-server-and-libraries-solid-control/5140
Maybe we should have a category of projects which people have started in different languages though code is not working now, like Gold (Is there a Rust one out there somewhere?)

On the commercial side there is ESS from Inrupt and Trinpod from Graphmetrix .

(Not sure of the status of Virtuoso from LDS).