fix(NcSelect): Use named export of VueSelect to prevent issues when imported in ESM projects

[susnux]

☑️ Resolves

TypeError: nextcloud_vue_select__WEBPACK_IMPORTED_MODULE_4_.props is undefined

With mixed exports the default is not imported but the whole exports object, can be tested with a simple script.
Just name this script some-name.mjs and run node ./some-name.mjs (of cause in that directory must be a node_modules with @nextcloud/vue-select installed).

import VueSelect from '@nextcloud/vue-select'
console.warn(VueSelect)

🏁 Checklist

• ⛑️ Tests are included or are not applicable
• 📘 Component documentation has been extended, updated or is not applicable

[ShGKme]

Makes sense

https://github.com/sagalbot/vue-select/blob/857753655adbebae612518aab072ed7f4a8deaa0/src/index.js#L4-L5