Allow staff to screen secondary filter violations

[emmiegit]

See also: #128

When processing whitespace/punctuation-squeezed filters, do not take the default action (e.g. delete or jail), but instead place three reactions, :white_check_mark:, :wastebasket: and :policeman:. If a moderator or higher reacts one on of them, that action is taken. Otherwise, if :white_check_mark: is clicked, then all the reactions are removed and the violation is removed. Other reactions, even by other staff, should be ignored past the first.