Migrate the gradebook to a react page

The gradebook page at /assignment/instructor/gradebook uses handson table. It would be nicer and more consistent to move it to React.

One limitation of this new implementation is that we can use the search box to filter the rows, but teachers would like to similarly filter the assignments to one or more assignments. Right now we can filter to one assignment.

In addition teachers would like to be able to click on a students score for a particular assignment to get a breakdown. I feel like this might be redundant with the grading interface, but if that work is re-usable giving them a second path to the information might be useful. (We should talk about this before you do it)