Add a button to notify (through direct casts) to TOP100 holders

[ferranrego]

When a Community vote is ongoing, allow admins to notify with direct casts the top 100 holders (by weight) who haven't voted yet.
This is translated in a new button next to the regular button that automatically selects these top 20 holders for notification.

Button text: "Remind TOP100 holders"

Or 3 buttons: TOP25, TOP50, TOP100