research: try out VUE3 compat release

[exalate-issue-sync]

User story

• As a developer I'd like to work with Vue 3 as soon as possible so that we can upgrade certain dependencies (like the vue router).

Acceptance criteria

• Check out the vue3 compat release https://github.com/vuejs/vue-next/tree/master/packages/vue-compat
• if easy to switch: just do it. If complicated: write down steps needed.
• don't spend more time than half a day

[pascalwengerter]

@kulmann @dschmidt can this be closed now? 😇

[kulmann]

yesssss :-)