Add Reaction Commerce provider

Signed-off-by: Loan Laux <loan@outgrow.io>

framework/reactioncommerce/cart/utils/fetcher.ts

@@ -0,0 +1,31 @@
+import { HookFetcherFn } from '@commerce/utils/types'
+import { Cart } from '@commerce/types'
+import { checkoutCreate, checkoutToCart } from '.'
+import { FetchCartInput } from '@commerce/cart/use-cart'
+
+const fetcher: HookFetcherFn<Cart | null, FetchCartInput> = async ({
+  options,
+  input: { cartId: checkoutId },
+  fetch,
+}) => {
+  let checkout
+
+  if (checkoutId) {
+    const data = await fetch({
+      ...options,
+      variables: {
+        checkoutId,
+      },
+    })
+    checkout = data.node
+  }
+
+  if (checkout?.completedAt || !checkoutId) {
+    checkout = await checkoutCreate(fetch)
+  }
+
+  // TODO: Fix this type
+  return checkoutToCart({ checkout } as any)
+}
+
+export default fetcher