Allow specifying multiple namespaces on test pages
Allow specifying multiple namespaces on test pages

Because GBD has 4 namespaces and we don't wanna go over one by one.

OurWorldInData/our-world-in-data-grapher,owid/owid-grapher,OurWorldInData/our-world-in-data-grapher,OurWorldInData/our-world-in-data-grapher,owid/owid-grapher,OurWorldInData/owid-grapher,OurWorldInData/owid-grapher,OurWorldInData/owid-grapher,OurWorldInData/our-world-in-data-grapher,owid/owid-grapher,owid/owid-grapher,OurWorldInData/owid-grapher,OurWorldInData/owid-grapher,owid/owid-grapher