Improve UI of "Add new URL" section

[agrabeli]

It was pointed out to us that when they first accessed the Test Lists Editor, they assumed that the "Add new URL" section pertained to the test list below. They thought that by selecting a category code (in the "Add new URL" section) that that would filter the rest of the list based on that category code.

This feedback suggests that it may not be immediately clear to users that the data entry slots under "Add new URL" are independent from the rest of the test list.

It therefore may be worth improving upon the UI of the "Add new URL" section in order to more clearly distinguish it from the rest of the test list. Perhaps it can have a frame and be larger?