Avoid class fields in lib/migrator.js

eslint doesn't like them without babel-eslint configured.

Author: Robert Jackson

lib/migrator.js

@@ -16,19 +16,16 @@ const { template } = require('jscodeshift');
 
 module.exports = class Migrator {
   /**
-   * @param {Options} options 
+   * @param {Options} options
    */
   constructor({ projectRoot, structure }) {
+    /** @type {string} */
     this.projectRoot = projectRoot;
+
+    /** @type {'flat' | 'nested'} */
     this.structure = structure;
   }
 
-  /** @type {string} */
-  projectRoot;
-
-  /** @type {'flat' | 'nested'} */
-  structure;
-
   get appRoot() {
     return path.join(this.projectRoot, 'app');
   }