Add a 'Keep-in-Touch' Unclassified Filter

As a user, I would like to be able to filter contacts by the keep-in-touch property with the value ‘unclassified’. The current filter in the All contacts view ‘No Keep-in-Touch Frequency’ combines BOTH ‘Unclassified’ and ‘Don’t keep in touch’ values.
https://www.screencast.com/t/CPMPlmQS9s