Support Vue 3

[ascott18]

A somewhat working version of coalesce-vue-vuetify3 exists and is published, but it still has problems. This is a tracking issue for its current known problems:

• [ ] Vuetify: Up/Down arrow keys can't be used for keyboard navigation of options in v-select/v-autocomplete
• [ ] Vuetify: v-date-picker/v-time-picker not releasing until Vuetify 3.1 https://github.com/vuetifyjs/vuetify/issues/13480
• [x] Vuetify: v-autocomplete no longer has prepend-item slot, preventing c-select's create prop from functioning.