feat: try to detect mailing lists as event attendees

[ChristophWurst]

The backend doesn't differenciate between individual email and a list. It will just send the invite. For a list, the invite is bogus and can't really be answered. We should warn the user.

[tcitworld]

Maybe also check for the KIND:group vCard parameter as possibly given by the ContactsManager ?

If the mail app knows that an e-mail address is a mailing-list through e-mail headers, it could also save it when adding the contact to the recently contacted contacts.

[kra-mo]

Good, but from a design side, the clipping text is obviously not ideal. Could the warning wrap and have sufficient space on the bottom?

[ChristophWurst]

I did not find an option for that in https://vue-select.org/guide/options.html#options-prop, unfortunately.

[kra-mo]

Can you add a hard line break, then? If not, the string should be shortened for now and this fixed upstream later.

For a shorter string, something like "List subscribers cannot accept invites."

Obviously not great for localization and a11y, but better than it being broken in default English.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[odzhychko]

Good, but from a design side, the clipping text is obviously not ideal. Could the warning wrap and have sufficient space on the bottom?

This is possible. I will update it the PR and mark it ready for review when done.