Fix overridden ESLint "import/no-extraneous-dependencies" rule

The import/no-extraneous-dependencies (1) rule allows to define a array
of glob pattern that are allowed to define import `devDependencies`. In
GH-15 the rule was overridden to include the project specific path
`**/.gatsby/**` which whitelists all Gatsby specific scripts.
Unfortunately this removes all glob pattern defined in the used
"eslint-config-arcticicestudio" (2) (rule is defined in the `-base`
package) resulting in errors in other projects paths like tests.
This has been fixed by importing the paths defined in the preset from
the "eslint-config-arcticicestudio-base" (3) package and merge it with
the additional **/.gatsby/**` path.

References:
  (1) https://github.com/benmosher/eslint-plugin-import/blob/master/docs/rules/no-extraneous-dependencies.md
  (2) https://www.npmjs.com/package/eslint-config-arcticicestudio
  (3) https://www.npmjs.com/package/eslint-config-arcticicestudio-base

Fixes GH-41

.eslintrc.js

@@ -17,6 +17,11 @@
  */
 
 const { resolve } = require("path");
+/* eslint-disable import/no-extraneous-dependencies */
+const {
+  rules: { "import/no-extraneous-dependencies": noExtraneousDependencies }
+} = require("eslint-config-arcticicestudio-base/rules/import/helpful-warnings");
+/* eslint-enable import/no-extraneous-dependencies */
 
 module.exports = {
   extends: "arcticicestudio",
@@ -38,8 +43,13 @@ module.exports = {
   rules: {
     "prettier/prettier": "error",
     "no-confusing-arrow": "off",
-    /* Suppress errors when importing development dependencies */
-    "import/no-extraneous-dependencies": ["error", { devDependencies: ["./.gatsby/**/*.js"] }],
+    /* Also suppress errors when importing development dependencies in project specific scripts. */
+    "import/no-extraneous-dependencies": [
+      "error",
+      {
+        devDependencies: noExtraneousDependencies[1].devDependencies.concat(["**/.gatsby/**"])
+      }
+    ],
     /*
      * Enable support for experimental features:
      *

.gatsby/onCreateWebpackConfig.js

@@ -17,11 +17,10 @@
  */
 
 const { resolve: resolvePath } = require("path");
-/* eslint-disable import/no-extraneous-dependencies */
+/* eslint-disable-next-line import/no-extraneous-dependencies */
 const webpack = require("webpack");
 const { BundleAnalyzerPlugin } = require("webpack-bundle-analyzer");
 const GitRevisionPlugin = require("git-revision-webpack-plugin");
-/* eslint-enable import/no-extraneous-dependencies */
 
 const { BASE_DIR_BUILD_REPORTS } = require("../src/config/internal/constants");