Support fetching references for a model

[pimeys]

We can jump to definition already, but we should also be able to list all lines where a model is referenced. This is in the protocol with the command textDocument/references and you can go on top of a model, list all references and see where the model is used in the data model.

[janpio]

Do you have a screenshot or gif of how this looks in other extensions?

[Druue]

This has been completed as part of prisma/prisma-engines#4934