message: beautify the json
diff: import browser from "webextension-polyfill";
  import parser from "ua-parser-js";
  +import { js_beautify as beautify } from "js-beautify";
  import { verifyFile, FileTypes, migrateTestCase, migrateProject } from "./legacy/migrate";
  import UiState from "../stores/view/UiState";
  import ModalState from "../stores/view/ModalState";
  @@ -73,7 +74,7 @@ function downloadProject(project) {
  Object.assign(project, Manager.emitDependencies());
  return browser.downloads.download({
  filename: project.name + ".side",
  - url: createBlob("application/json", JSON.stringify(project)),
  + url: createBlob("application/json", beautify(JSON.stringify(project), { indent_size: 2 })),
  saveAs: true,
  conflictAction: "overwrite"
  });
  