feat: add gateway-neutral payment package

packages/payment/components/PaymentMethodList.wrn

@@ -0,0 +1,4 @@
+component PaymentMethodList {
+  props { methods: array = [] }
+  view { <ul class="wrn-payment-methods">{#each methods as method}<li>{method.brand} ending {method.last4}</li>{/each}</ul> }
+}