title: Perform git sparse-checkout of everything except a list of subdirectories
body: <p>I have the following (mono)repo structure</p>
  <pre><code>└── dir1
      ├── subdir1
      │   ├── subdir1a
      │   ├── subdir1b
      │   └── subdir1c
      └── subdir2
          ├── subdir2a
          ├── subdir2b
          ├── subdir2c
  
  └── dir2
  └── dir3
  </code></pre>
  <p>I want to checkout everything <strong>except</strong> (say) <code>subdir1b</code> and <code>subdir1c</code>.</p>
  <p>Is there a way to perform a sparse checkout of <strong>everything</strong> except perhaps some subdirs?</p>
  <p>Asking because perhaps (if there is such a work around) it is easier to state to <code>git</code> what you do <strong>not</strong> want to be checkout rather than start listing everything that is to be checkout.</p>