title: Format document on save with Remove unused usings on vscode
body: <p>I want to setup to fire "format document" and "remove unused usings" on save for C# code on Visual Studio Code. Or add a keyboard shortcut for remove unused usings.</p>
  
  <p>I have added to user settings below.</p>
  
  <pre><code>"editor.formatOnSave": true
  </code></pre>
  
  <p>This fires format document on save. But I want also to remove unused usings.
  VS code warns me if there are unused usings and I can Ctrl + . to popup about remove unused usings.</p>
  
  <ol>
  <li>Can I setup fire remove unused usings on save?</li>
  <li>Can I add a keyboard shortcut for the remove unused usings?</li>
  </ol>
  
  <p>I also added keyboard shortcut for format document.</p>
  
  <pre><code>{ "key": "ctrl+k ctrl+f",         "command": "editor.action.formatSelection",
                                    "when": "editorHasDocumentSelectionFormattingProvider &amp;&amp; editorHasSelection &amp;&amp; editorTextFocus &amp;&amp; !editorReadonly" },
  </code></pre>
  
  <p>I want to add Ctrl+R Ctrl+G for remove unused usings. (by Visual Studio defaults). But I don't know how I can configure keyboard shortcut settings...</p>
  
  <pre><code>{ "key": "ctrl+r ctrl+g",         "command": "editor.action.???",
                                    "when": "???" },
  </code></pre>