* A new accepted-cards element to represent the labeled list of card icons
* Add the accepted cards section to the summary and card add/edit page
* mochitest for the accepted-cards element
* Make cc-type a required field and validate it against the list of supported networks
* Add verification of the pay button disabling when card network is not supported
Depends on D5823
Differential Revision: https://phabricator.services.mozilla.com/D5824
579931d05b