[ical4j 4.x] Test with vivaldi.net

[rfc2822]

Created from checklist item in #241.

Original text:

vivaldi.net

[sunkup]

• collection detection does not work / server sends 404. In our wiki there is a comment: "caldav completely broken"

[cketti]

Worked for me when following these steps: https://help.vivaldi.com/services/webmail/web-calendar/#Sync_your_calendars_using_CalDAV

Tested with an Android 13 emulator.

• Event added on server syncs to device
• Event added on device syncs to server
• Event changed on server syncs to device
• Event changed on device syncs to server
• Event deleted on server syncs to device
• Event deleted on device syncs to server
• Recurring event with exception works fine when created/modified on device. Otherwise problematic; see [ical4j 4.x] Adding EXDATE to recurring event using UTC #328
• Task added on device syncs to server
• Task changed on device syncs to server
• Task deleted on device syncs to server