✨ feat: Add relay docker image

[wanjohiryan]

Description

What(what issue does this code solve/what feature does it add):

We are adding the Dockerfile to build a moq-relay

How(how does it solve it):

1. Added relay.Dockerfile with all the docker code to build kixelated's moq-relay.
2. Added relay.yml in workflows for building and publishing the docker image

Required Checklist:

• I have added any necessary documentation and comments in my code (where appropriate)
• I have added tests to make sure my code runs in all contexts

Further comments