add e2e test for payment mfe (#2543)
add e2e test for payment mfe (#2543)

Note: Intentionally not making overly DRY since it shouldn't be
long before we remove the old basket page test.

ARCH-998
edx/ecommerce,edx/ecommerce,eduNEXT/edunext-ecommerce,eduNEXT/edunext-ecommerce,eduNEXT/edunext-ecommerce,edx/ecommerce,edx/ecommerce,eduNEXT/edunext-ecommerce