Adding common CDS GitHub actions

[sylviamclaughlin]

Summary | Résumé

Adding common GitHub workflows that we use at CDS:

1. Dependency review - uses a GitHub native action that scans a pull request for dependency changes and raises any errors if vulnerabilities or invalid licenses are used. (https://github.com/actions/dependency-review-action)
2. Export GitHub data - uses 2 Github workflows created by CDS - DNS Proxy Action that allows you to do some basic safe- and block-listing of domains on your Ubuntu GitHub Action runners and the GitHub repository metadata exporter that collects metadata about a repository and sends it to Azure Sentinel.
3. Labels - A CDS custom workflow called CDS Github Standard Labels that syncs a repo's issue labels with the set defined in RFC 0003 CDS Github Label Standard.
4. OSSF Scorecard - for public repositories, it uses the ossf scorecard GitHub action that checks the security practice and risk of the project.
5. S3 backup - backs up all the repo's data daily to an S3 bucket in our AWS environment. Essentially, this creates a backup of the repo.
6. Shellcheck - performs static analysis on shell scripts located in .github/workflows/scripts. Even though right now you don't have any such scripts, it is still a good idea to include this in case you add such scripts in the future.