Go-to-Definition for OML code

[0x65-e]

User Story

As a User, I would like to quickly find the definition of an OML entity so that I can quickly find the context of a reference when reading and writing OML documents.

Detailed Description

Go-to-definition is one of the most basic and most helpful features of a language server. Go-to-definition should work across source files, so that a reference to a definition in another document can be easily found.

Acceptance Criteria

• [x] Given I right click on a reference to a local entity, then I jump to the local definition
• [x] Given I right click on a reference to an entity in a separate file, then the other file with the definition should open

[0x65-e]

Local entity reference is working with the default Langium implementation after @Jeff848's fix for scope computation. Cross-file support still requires work for namespace and linking.