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/auth/use-signup.tsx

@@ -0,0 +1,68 @@
+import { useCallback } from 'react'
+import { MutationHook } from '@commerce/utils/types'
+import { CommerceError, ValidationError } from '@commerce/utils/errors'
+import useSignup, { UseSignup } from '@commerce/auth/use-signup'
+import useCustomer from '../customer/use-customer'
+import {
+  RegisterCustomerInput,
+  SignupMutation,
+  SignupMutationVariables,
+} from '../schema'
+import { signupMutation } from '../lib/mutations/sign-up-mutation'
+
+export default useSignup as UseSignup<typeof handler>
+
+export type SignupInput = {
+  email: string
+  firstName: string
+  lastName: string
+  password: string
+}
+
+export const handler: MutationHook<null, {}, SignupInput, SignupInput> = {
+  fetchOptions: {
+    query: signupMutation,
+  },
+  async fetcher({
+    input: { firstName, lastName, email, password },
+    options,
+    fetch,
+  }) {
+    if (!(firstName && lastName && email && password)) {
+      throw new CommerceError({
+        message:
+          'A first name, last name, email and password are required to signup',
+      })
+    }
+    const variables: SignupMutationVariables = {
+      input: {
+        firstName,
+        lastName,
+        emailAddress: email,
+        password,
+      },
+    }
+    const { registerCustomerAccount } = await fetch<SignupMutation>({
+      ...options,
+      variables,
+    })
+
+    if (registerCustomerAccount.__typename !== 'Success') {
+      throw new ValidationError(registerCustomerAccount)
+    }
+
+    return null
+  },
+  useHook: ({ fetch }) => () => {
+    const { revalidate } = useCustomer()
+
+    return useCallback(
+      async function signup(input) {
+        const data = await fetch({ input })
+        await revalidate()
+        return data
+      },
+      [fetch, revalidate]
+    )
+  },
+}