feat: allow using runtimeConfig to set sanity options

see nuxt/nuxt#7950

templates/plugin.js

@@ -1,26 +1,28 @@
 import Vue from 'vue'
+import defu from 'defu'
 
 <%= options.client
   ? "import createClient from '@sanity/client'"
   : "import { createClient } from '@nuxtjs/sanity'"
 %>
 
 <% if (options.components.imageHelper) { %>
-  import { SanityImage } from './sanity-image'
-  Vue.component('SanityImage', SanityImage)
+import { SanityImage } from './sanity-image'
+Vue.component('SanityImage', SanityImage)
 <% } %>
 
 <% if (options.components.contentHelper) { %>
-  import { SanityContent } from '@nuxtjs/sanity/dist/sanity-content'
-  Vue.component('SanityContent', SanityContent)
+import { SanityContent } from '@nuxtjs/sanity/dist/sanity-content'
+Vue.component('SanityContent', SanityContent)
 <% } %>
 
-const options = JSON.parse('<%= options.sanityConfig %>')
+const _options = JSON.parse('<%= options.sanityConfig %>')
 
 /**
  * @type {import('@nuxt/types').Plugin}
  */
-export default async (_ctx, inject) => {
+export default async ({ $config }, inject) => {
+  const options = defu($config.sanity || {}, _options)
   inject('sanity', {
     client: createClient(options),
     fetch(...args) {