Build container images on Github Actions and push to multiple registries (#26247)

Modifications:
- Modify the workflow to build container images without pushing when the workflow file itself is modified
- Strip the leading ghcr.io/spack/ from env.container env.versioned to prepare pushing to multiple registries
- Fixed CentOS 7 and Amazon Linux builds
- Login and push to Docker Hub as well as Github Action
- Add a badge to README.md with the status of docker images

README.md

@@ -4,6 +4,7 @@
 [![Bootstrapping](https://github.com/spack/spack/actions/workflows/bootstrap.yml/badge.svg)](https://github.com/spack/spack/actions/workflows/bootstrap.yml)
 [![macOS Builds (nightly)](https://github.com/spack/spack/workflows/macOS%20builds%20nightly/badge.svg?branch=develop)](https://github.com/spack/spack/actions?query=workflow%3A%22macOS+builds+nightly%22)
 [![codecov](https://codecov.io/gh/spack/spack/branch/develop/graph/badge.svg)](https://codecov.io/gh/spack/spack)
+[![Containers](https://github.com/spack/spack/actions/workflows/build-containers.yml/badge.svg)](https://github.com/spack/spack/actions/workflows/build-containers.yml)
 [![Read the Docs](https://readthedocs.org/projects/spack/badge/?version=latest)](https://spack.readthedocs.io)
 [![Slack](https://slack.spack.io/badge.svg)](https://slack.spack.io)