Add `microk8s.inspect`?

Kubeflow charms also have microk8s.inspect which could be handy.

    - name: Generate inspect tarball
      run: >
        sg microk8s <<EOF
          microk8s inspect | \
          grep -Po "Report tarball is at \K.+" | \
          xargs -I {} cp {} inspection-report-${{ strategy.job-index }}.tar.gz
        EOF
      if: failure()

    - name: Upload inspect tarball
      uses: actions/upload-artifact@v2
      with:
        name: inspection-reports
        path: ./inspection-report-${{ strategy.job-index }}.tar.gz
      if: failure()