Merge branch 'dd/ci-swap-azure-pipelines-with-github-actions'

Merge branch 'dd/ci-swap-azure-pipelines-with-github-actions'

Update the CI configuration to use GitHub Actions, retiring the one
based on Azure Pipelines.

* dd/ci-swap-azure-pipelines-with-github-actions:
  ci: let GitHub Actions upload failed tests' directories
  ci: add a problem matcher for GitHub Actions
  tests: when run in Bash, annotate test failures with file name/line number
  ci: retire the Azure Pipelines definition
  README: add a build badge for the GitHub Actions runs
  ci: configure GitHub Actions for CI/PR
  ci: run gem with sudo to install asciidoctor
  ci: explicit install all required packages
  ci: fix the `jobname` of the `GETTEXT_POISON` job
  ci/lib: set TERM environment variable if not exist
  ci/lib: allow running in GitHub Actions
  ci/lib: if CI type is unknown, show the environment variables