"contributes": {
  "commands": [
    {
      "command": "command.id",
      "title": "My View Action",
      "icon": {
        "light": "resources/light/refresh.svg",
        "dark": "resources/dark/refresh.svg"
      }
    }
  ],
  "menus": {
    "view/title": [
      {
        "command": "command.id",
        "when": "view == your.view.id",
        "group": "navigation"
      }
    ]
  }
}

You can refer to https://code.visualstudio.com/api/extension-guides/tree-view#view-actions