Changed setup helpers+test for onepagecheckout

* Added individual helpers for setting up different checkouts.
* Added test that runs on onepagecheckout
Split test into two tests
Moved test bodies into seperate functions

The disabled/not disabled tests will run on so many inputs that they can
have single implementations.
Changed from testing disabled to testing readonly

The inputs should be readonly, not disabled.
Invalid country div tests
Setting inputs to readonly instead of disabled
Support for use_for_shipping_yes

* Support for toggling/hiding use_for_shipping_yes
* svea-hidden class is tested instead of readonly
Support for displaying method not available