add a github action for build multi-arch docker images (#1574)
add a github action for build multi-arch docker images (#1574)

## Issue Addressed

#1512

## Proposed Changes

Use Github Actions to automate the Docker image build, so that we can make a multi-arch image.  

## Additional Info

This change will require adding the DOCKER_USERNAME and DOCKER_PASSWORD secrets in Github. It will also require disabling the Docker Hub automated build. 




sigp/lighthouse,sigp/lighthouse,sigp/lighthouse,sigp/lighthouse