ESLint: fixup the configuration of the import/no-extraneous-modules

Don't specify a `packageDir` and make it look at the closest `package.json` by default.

Also, add `lodash` as a top-level dev dependency, as some build-only files (e.g., `.eslintrc`)
use it.

.eslintrc.js

@@ -174,6 +174,6 @@ module.exports = {
 
 		// Disallow importing or requiring packages that are not listed in package.json
 		// This prevents us from depending on transitive dependencies, which could break in unexpected ways.
-		'import/no-extraneous-dependencies': [ 'error', { packageDir: './' } ],
+		'import/no-extraneous-dependencies': 'error',
 	},
 };

package.json

@@ -210,6 +210,7 @@
 		"jest-junit": "9.0.0",
 		"lerna": "3.18.4",
 		"loader-utils": "1.2.3",
+		"lodash": "4.17.15",
 		"md5-file": "4.0.0",
 		"mixedindentlint": "1.2.0",
 		"mkdirp": "0.5.1",