Adds project handles to task cards on workboards, as discussed in T4863.
This also adds a new option, projects.projects-in-workboards, which enables/disables
this feature. As discussed in T4863, showing projects is the default.
The existing behavior for showing multiple attributes on cards (e.g. both the owner
and the projects) was to show them on the same line with a middot between. I
though this looked bad with the new project handles, so I also modified the CSS
for workboards to break them into separate lines. It looks like this: