CI: enable the 'ccache' compiler cache on Windows and macOS
CI: enable the 'ccache' compiler cache on Windows and macOS
CI: 'linux-build' becomes 'linux-build-and-test'; use ccache for both Linux builds
CI: refactor the pre-commit jobs
CI: don't upload artifacts of failed 'linux-build-and-test' jobs
CI: harmonize the pre-commit job definitions with the FlightGear repo
CI: use $BRANCH_REF rather than 'next' in cache key names
CI: 'linux-build' becomes 'linux-build-and-test'; use ccache for both Linux builds