Ask for confirmation when mentioning all in a large conversation

[ChristophWurst]

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Is your feature request related to a problem? Please describe.

As a Nextcloud Talk user I often get notifications for someone using the @all mention in a chat room with many participants even though the message is not urgent nor does everyone have to see the message.

Describe the solution you'd like

Ask the mentioner for confirmation so they are warned about the impact. Somethine like You are about to mention x people who receive a notification.

The threshold for the confirmation could be at 10 participants.

Describe alternatives you've considered

N/a

Additional context

N/a