Nearly complete lifting card-move code out of workboards

Summary: Ref T10010. This gets rid of the last dependency on the weird ColumnPositionQuery code.

Test Plan:

• Viewed workboards.
• Used batch editor.
• Created a new workboard.
• Dragged stuff around.
• Created new tasks into columns.
• Changed order from natural to priority, dragged things around.
• Switched filter to custom filter, "all tasks", etc.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10010

Differential Revision: https://secure.phabricator.com/D15176