Add runOutsideVue option to vue/sort-keys

[lukethompson]

Address issue raised here https://github.com/vuejs/eslint-plugin-vue/issues/1865

Update vue/sort-keys to use existing options.runOutsideVue option, it seems like previously this option did not do anything.

If this change gets accepted we should update the docs to state which version this option will be available from 😄