Add ESLint configuration file

Introduces .eslintrc.js with WordPress recommended settings and customizes import/no-unresolved rule to ignore @wordpress/ imports.

Author: mtoensing

.eslintrc.js

@@ -0,0 +1,11 @@
+module.exports = {
+	extends: [ 'plugin:@wordpress/eslint-plugin/recommended' ],
+	rules: {
+		'import/no-unresolved': [
+			'error',
+			{
+				ignore: [ '^@wordpress/' ],
+			},
+		],
+	},
+};