Move workboard "View as Query" workflow to a separate controller
This makes one material improvement: previously, we built the full board and did layout on all the cards before building the query. However, we do not actually need to do this: we don't need the cards. Instead, just do layout without handing over any card PHIDs. This is slightly faster, particularly on large boards.
- Clicked "View as Query" on a board, got a query page for the column.
- Applied a custom filter, then clicked "View as Query" on a board. Got a query page merging the two filters.
- Applied a custom filter, then clicked "Veiw as Query" on a board, in a subproject column. Got a query page merging the two filters, respecting the project-ness of the column.
Reviewed By: amckinley
Maniphest Tasks: T4900
Differential Revision: https://secure.phabricator.com/D20633