[vue3] Migration strategy

[grolu]

Define a migration strategy for vue3

Current plan:

• Do not migrate components to Composition API (yet)
• Migrate store to pinia, use compatibly functions for options API
• Upgrade vuetify2 to vuetify3
• Do not try to solve issues or refactor code
• Add (small) reusable components to align UI

This also includes ramp up activity and build-up knowledge to decide properly.

[grolu]

done /close