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