Table bulk actions

Low priority because we can't actually do this yet on the API side and I'm not about to fire off a request for every selected row. But it will come in handy to have a generic thing in the table controls that takes a list of bulk actions, something like

{ 
  label: ReactNode , 
  action: (selectedRows: Row[]) => void 
}

action could take IDs instead of the whole rows, but if everything is done by name, then we'll need names instead. Passing rows is more flexible, with no downside that I can see.

No file or test is named. Start by locating the table controls and row-selection implementation, then check how the API-side limitation affects the design. Done means the table controls can accept generic bulk actions and invoke an action with the selected rows when the supporting API work is available.