Make more robust grade types

[jiachengzhang1]

P and F have different meaning but they are essentially the same in the CourseRecord. e.g. https://catalog.arizona.edu/policy/grades-and-grading-system

[halyusuf25]

Universities have different grading systems and grading letters. It will be helpful if the toolbox can provide a parametrized grading system that the user can create before using the other toolbox features