Community trudag plugins

Problem/Objective Summary

• Currently, the only trudag reference/validator plugins available to the public are the core ones.
• We need to setup a trudag-plugins repository to host a bunch of useful plugins that the open source community can use to perform a variety of functions.

Steps to reproduce (Optional)

Relevant logs and/or screenshots (Optional)

Definition Of Done

• trudag-plugins repository is hosted on https://gitlab.eclipse.org/eclipse/tsf/