R1:9ea7227f0fc9

Move workboard "View as Query" workflow to a separate controller

Summary:
Depends on D20632. Ref T4900. As with other workflows on the board controller, this one is currently in the giant main "do everything" method. Move it 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…