Calendar view for events (and other modules with DateRanges)

[didoda]

This introduces a calendar view in index for modules that have "DateRanges" association.

This uses fullcalendar/vue: https://fullcalendar.io/docs/vue

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.80%. Comparing base (a0066b2) to head (68c3429).
⚠️ Report is 3 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #1251   +/-   ##
=========================================
  Coverage     99.80%   99.80%           
- Complexity     1452     1454    +2     
=========================================
  Files           101      101           
  Lines          5663     5669    +6     
=========================================
+ Hits           5652     5658    +6     
  Misses           11       11           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.