Function deltachat::receive_imf::apply_group_changes

async fn apply_group_changes(
    context: &Context,
    mime_parser: &mut MimeMessage,
    chat_id: ChatId,
    from_id: ContactId,
    to_ids: &[ContactId],
    is_partial_download: bool,
    verified_encryption: &VerifiedEncryption
) -> Result<(Vec<String>, Option<String>)>

Apply group member list, name, avatar and protection status changes from the MIME message.

Optionally returns better message to replace the original system message. is_partial_download: whether the message is not fully downloaded.