title: vscode extension change color of title bar
body: <p>I'm writing a vsCode extension, and from all their API I can't find how to edit colors, either of the active tab, or the title bar. All I can see is adding a status bar item.</p>
  
  <p>What I have:</p>
  
  <pre><code>  let disposable = vscode.window.onDidChangeActiveTextEditor((e: vscode.TextEditor | undefined) =&gt; {
  
          if (!e) return null;
  
          var currentlyOpenTabfilePath = e.document.fileName;
  
          const color = 'green';
          changeColorInTitleBar(color) // This is what I need
  
      })
  </code></pre>
  
  <p>package.json:</p>
  
  <pre><code>  "menus": {
              "editor/title": [{
                  "when": "textInputFocus == true",
                  "command": "extension.sayHello",
                  "group": "navigation"
              }]
          }
  </code></pre>
  
  <p>Should I edit the workspace.settings from the extension? or is there a vscode API way of doing it?</p>