Shopify Provider (#186)

* Start of Shopify provider

* add missing comment to documentation

* add missing env vars to documentation

* update reference to types file

framework/shopify/api/operations/get-all-collections.ts

@@ -0,0 +1,21 @@
+import Client from 'shopify-buy'
+import { ShopifyConfig } from '../index'
+
+type Options = {
+  config: ShopifyConfig
+}
+
+const getAllCollections = async (options: Options) => {
+  const { config } = options
+
+  const client = Client.buildClient({
+    storefrontAccessToken: config.apiToken,
+    domain: config.commerceUrl,
+  })
+
+  const res = await client.collection.fetchAllWithProducts()
+
+  return JSON.parse(JSON.stringify(res))
+}
+
+export default getAllCollections