title: How can I let vscode know when SCM visible or not?
body: <p>I would like to make toggle key with VScode's keybinding.
  with alt + 1 to 5 to toggle explorer and search, scm, debug extension</p>
  
  <p>I could find "explorerViewletVisible" or "searchViewletVisible"
  But I couldn't find visibilities of scm (source control) and debug, extensions.
  I use "sideBarVisible" for these key but it is not a perfect solution.
  Does Anyone know right 'when expression' of these situations?</p>
  
  <pre><code>  {
      "key": "alt+1",
      "command": "workbench.view.explorer",
    },
    {
      "key": "alt+1",
      "command": "workbench.action.toggleSidebarVisibility",
      "when": "explorerViewletVisible"
    },
    {
      "key": "alt+2",
      "command": "workbench.view.search",
    },
    {
      "key": "alt+2",
      "command": "workbench.action.toggleSidebarVisibility",
      "when": "searchViewletVisible"
    },
    {
      "key": "alt+3",
      "command": "workbench.view.scm",
    },
    {
      "key": "alt+3",
      "command": "workbench.action.toggleSidebarVisibility",
      "when": "sideBarVisible"
    },
  </code></pre>