Add workflows for dev, nightly, and release Docker containers

[dsikka]

Summary

• Add a workflow which based on the conditions, will create a nightly, dev or release container
• So far, the workflows rely on a cuda-based Python 3.8 docker image from nm-docker https://github.com/neuralmagic/nm-docker/pull/1. This source image is a build arg and can be updated to be whatever python version is required by the workflow
• The following cases are covered:

1. Dev

• For dev, a container is created if a PR to main is opened or updated
• sparseml will be cloned using the specific branch and an editable install will be used to install all packages
• The container will be tagged with the PR number when pushed to GCR

2. Release

• When a PR is opened/updated to a release branch: in that case, sparseml will be installed using the specific version of the release

3. Nightly

• When a PR is merged into main, sparseml will install the latest nightly build
• A scheduled nightly cron job will trigger a nightly build and create a container with the most recent nightly build

Testing

• Nightly and dev workflows have been tested and containers are currently being pushed to packages
• Release builds have not been tested

Next Steps:

• Update the names of the containers in GCR. So far using dummy test names but will need slight updating to consider the different workflows
• Find a non-destructive way to test release workflows