Automatically preview website on PR

[dlebauer]

1. Mirror the .github/workflows/publish-docs.yml workflow added to SIPNET (Consolidate docs deployment workflows sipnet#191) to:

This will:

• Build docs on push and PR.
• Publish preview associated with the changes.
• Deploy when PR is merged.

2. Remove actions that are no longer needed

3. [Optional]: make sure it works on forked repositories.

4. Once the PR is submitted or ready to submit, the following settings need to be changed by a maintainer:

• change build and deploy from 'deploy from a branch' to 'GitHub actions' (settings --> pages --> build and deploy)
• Make sure the following are enabled
  • "Read and write permissions" for GITHUB_TOKEN (settings -> actions -> general --> workflow permissions
  • "Allow GitHub Actions to deploy to GitHub Pages” (settings --> actions --> general --> workflow permissions
• Require status check for the job