[TB] FINOS Publish container image to public registry

## Problem/Concern

The goal of this issue is to develop a process, establish a CI/CD pipeline, and publish a container image of Theme Builder to a publicly-available registry. This would make it much easier for non-developers to "kick the tires" with Theme Builder, especially in the near term before we have Theme Builder deployed in the FINOS environment. The container image could eventually be used in deployments, too.

It would be wonderful if this could be completed in anticipation of the Grace Hopper event which is on 09/22.

## Proposed Solution