migrating logic relating to relation between domains and vocavs into a common library

[jad-elkhoury]

Migrating logic relating to relation between domains and vocavs into a common library Aim for this library is to reused by the code generator for consistency.

Checklist

• [X] This PR adds an entry to the CHANGELOG. _See https://keepachangelog.com/en/1.0.0/ for instructions. Minor edits are exempt.
• [ ] This PR expects some manual changes to the generated code. The needed changes are detailed in the CHANGELOG entry.
• [X] This PR was tested with at least one code generation, resulting in a working OSLC server.
• [X] This PR does NOT break the user block code

[jad-elkhoury]

@berezovskyi Can I aks you to please do a review of this change? I happened to merge already to mater 👎 One imprtant question relates to the plugins update site. Should we use edge or stable? How does this affect our process when we try to release?

https://github.com/eclipse/lyo.designer/blob/57459d2ffd60530542e125389e6b9c667b87ae3d/pom.xml#L15