Provide a Graphical Language Server Protocol Server for UVL

[gravemalte]

We need unified exchange format for a graphical view. Clients should be able to render UVL diagrams without always to self craft solutions. Instead, we should rely on a fixed protocol. Such an option would be the Graphical Language Server Protocol (GLSP).

https://eclipse.dev/glsp/

[SundermannC]

@gravemalte will lead further discussions on this topic.

[SundermannC]

We are currently working on a GLS for feature models mostly focused on UVL constructs within FeatJAR. Some elements still require further tailoring to match expected feature model visuals and the controls are sometimes clumsy, but it might be a good starting point.