[Op Readiness: P0]: publish frontend and backend docker images to github container registry

[SgtPooki]

They should be built on merge to main and tagged with commit sha sha-*. These images will immediately be pulled by filoz-infra flux CD for deployment of the staging environment

When ready for prod release, we should add a semver tag (e.g. 1.x.x). These images will immediately be pulled by filoz-infra flux CD for deployment of the production environment.

this should essentially follow the same pattern as https://github.com/filecoin-project/filoz-infra/blob/main/.github/workflows/ecr.yml

dependsOn #85

[SgtPooki]

we are no longer planning on using filoz-infra, so publishing to AWS has been removed.