Refactor new_dropdown/index to receive isOpen prop
**Why?** Previously it managed this as an internal data property, but there was extra complexity involved because the component doesn't have all the information it needs (i.e. the `mouseOver` prop). This is a good opportunity to colocate the data prop with the component that has the information to change it (i.e. `file_row`) and let `new_dropdown/index` receive this value as a prop.