refactor!: Migrate to vue3

[susnux]

• alternative for, closes feat(vue3): migrate to vue3 #884
• resolves Upgrade to Vue 3.x #1369

• Adjust dependencies for Vue 3
• Adjusted documentation: This package is now also compatible with Vue 3 and Vue 2 (while when using Vue 3 in app the bundle size is smaller)
• Adjusted code to Vue 3
  • Due to already using <script setup> we do not need to touch the components a lot, only drop second <script> as the name is now automatically inferred by the filename with Vue 3 and script setup.
  • props vs propsData
  • v-model:prop vs :prop.sync
  • 💥 drop deprecated Dialog.hide which allows us to use spawnDialog from @nextcloud/vue also for Vue 3
  • 💥 drop filepicker component export to make the package Vue version agnostic

I also tested this with server and it seems to work fine.