PickBlock should use the output port of the picked representation

This fixes #17176 (closed). @jacob @utkarsh.ayachit

My follow up branch to fix the other crash I found will have to wait since it is taking longer. This will prevent the crash in creating the context menu, but the menu items for block actions (set opacity, visibility, color) will crash or behave strangely unless the multiblock dataset is selected in the pipeline (is active representation). Right now they grab the active representation and hope it is the right one. I will push up my current branch to fix this and put some notes on it about remaining as a separate PR.