Implement custom checkout (#487)

* Implement custom checkout core

* Fix elements on core

* Add files to providers

* Adapt providers

* Update types

* Update shopify file

* Format files

framework/shopify/customer/address/use-add-item.tsx

@@ -0,0 +1,15 @@
+import useAddItem, { UseAddItem } from '@commerce/customer/address/use-add-item'
+import { MutationHook } from '@commerce/utils/types'
+
+export default useAddItem as UseAddItem<typeof handler>
+
+export const handler: MutationHook<any> = {
+  fetchOptions: {
+    query: '',
+  },
+  async fetcher({ input, options, fetch }) {},
+  useHook:
+    ({ fetch }) =>
+    () =>
+    async () => ({}),
+}

framework/shopify/customer/card/use-add-item.tsx

@@ -0,0 +1,15 @@
+import useAddItem, { UseAddItem } from '@commerce/customer/card/use-add-item'
+import { MutationHook } from '@commerce/utils/types'
+
+export default useAddItem as UseAddItem<typeof handler>
+
+export const handler: MutationHook<any> = {
+  fetchOptions: {
+    query: '',
+  },
+  async fetcher({ input, options, fetch }) {},
+  useHook:
+    ({ fetch }) =>
+    () =>
+    async () => ({}),
+}