frontend: add simple part of vue/vue3-recommended rules
Turn off the following rules for now: "vue/no-deprecated-dollar-scopedslots-api": "off", "vue/no-deprecated-slot-attribute": "off", "vue/no-deprecated-slot-scope-attribute": "off", because i could not get the new syntax to work.
That we are ready for vue3 as soon as the calendar works. Issue: #5121
Feature branch deployment currently inactive.
If the PR is still open, you can add the deploy! label to this PR to trigger a feature branch deployment.
Seems that the lint rule rewrites the event identifier where you register the event, but not the place where you emit the event. Fixed with https://github.com/ecamp/ecamp3/pull/5170/commits/fc71576bb37bd0143a1db3a4b7eb7dc4b4138032
More rule applications were here: #5122