Add instance-variables to react/sort-comp

[amannn]

Would be useful in order to support someRef = React.createRef().

See jsx-eslint/eslint-plugin-react#1879

[amannn]

Seems like there are still issues with this (see linked thread above).

[jamesjara]

     "react/sort-comp": [1, {
        "order": [
          "type-annotations",
          "static-methods",
          "static-variables",
          "instance-variables",
          "/^on.+$/",
          "lifecycle",
          "everything-else",
          "render",
        ],
      }]
    },```
hope it works