workboards - make errors from filtering show up

Summary: Fixes T7252. The UI is slightly different than in Maniphest - in Maniphest the error shows up at the bottom and here it shows up the top - but I think the UI here makes sense as you see the error right away on the newly returned dialogue?

Test Plan: set "created after" to "assdaasds" and got an error back. set filter to something that should work and it worked

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T7252

Differential Revision: https://secure.phabricator.com/D11760