R1:fb765b8c93fe

Add language and date ranges to Paste queries

Summary:
Ref T2625. Ref T3273. This is mostly a UI foil for T3273. Right now, to find tasks without owners or without projects you search for the magic strings "upforgrabs" and "noproject". Unsurprisingly, no users have ever figured this out. I want to get rid of it. Instead, these interfaces will look like:

Assigned: [ Type a user name... ]
[ X ] Find unassigned tasks.
Projects: [ Type a project name... ]
[ X ]…