Vendure provider (#223)

* Minimal list/detail views working with Vendure

* Implement useCart/useAddItem

* Implement useUpdateItem & useRemoveItem

* Implement useSearch

* Add operations codegen, tidy up

* Dummy checkout page

* Implement auth/customer hooks

* Use env var for Shop API url

* Add some documentation

* Improve error handling

* Optimize preview image size

* Fix accidental change

* Update Vendure provider to latest changes

* Vendure provider: split out gql operations, remove unused files

* Update Vendure provider readme

* Add local next.config to Vendure provider, update docs

* Update to use demo server

* Fix build errors

* Use proxy for vendure api

* Simplify instructions in Vendure readme

* Refactor Vendure checkout api handler

* Improve image quality

framework/vendure/customer/use-customer.tsx

@@ -0,0 +1,33 @@
+import { SWRHook } from '@commerce/utils/types'
+import useCustomer, { UseCustomer } from '@commerce/customer/use-customer'
+import { Customer } from '@commerce/types'
+import { ActiveCustomerQuery } from '../schema'
+import { activeCustomerQuery } from '../lib/queries/active-customer-query'
+
+export default useCustomer as UseCustomer<typeof handler>
+
+export const handler: SWRHook<Customer | null> = {
+  fetchOptions: {
+    query: activeCustomerQuery,
+  },
+  async fetcher({ options, fetch }) {
+    const { activeCustomer } = await fetch<ActiveCustomerQuery>({
+      ...options,
+    })
+    return activeCustomer
+      ? ({
+          firstName: activeCustomer.firstName ?? '',
+          lastName: activeCustomer.lastName ?? '',
+          email: activeCustomer.emailAddress ?? '',
+        } as any)
+      : null
+  },
+  useHook: ({ useData }) => (input) => {
+    return useData({
+      swrOptions: {
+        revalidateOnFocus: false,
+        ...input?.swrOptions,
+      },
+    })
+  },
+}