Allow learners to filter by credit and credit type in course catalog

Allow learners to filter by credit and credit type in the course catalog. Right now the only way to find courses with credits is to look at the individual course or for admin to create a catalog folder of courses that offer credits, which is inefficient, especially for courses that offer multiple credit types. A work around we are going to try is adding tags that list the credit and credit type, but this is time-consuming and has to be done manually for each course.