Mass bug manipulation not team aware

When the maintainer of, for example, an upstream product, is looking at the list of bugs on their product, they should see a checkbox beside each bug allowing them to mass-manipulate the tasks (currently the only kind of mass manipulation one can do is milestone assignment, but this could, of course, include mass assignment or other things.)

These checkboxes are not rendered when the person looking at the bug list is the member of a team that is set as the owner of the upstream. The mass-manipulation interface (i.e. the checkbox beside bug task) should be rendered when the person looking at the bug list is either directly the maintainer of the thing on which these tasks are filed, or when they are a maintainer by way of team participation.