message: add electron test step to precheckin step
diff: "format-check": "prettier --config prettier.config.js --check \"**/*\"",
  "generate-scss-typings": "tsm \"src/**/*.scss\"",
  "clean:scss-typings": "grunt clean:scss",
  - "precheckin": "npm-run-all --serial clean:scss-typings format-check tslint copyrightheaders build:all test test:e2e",
  + "precheckin": "npm-run-all --serial clean:scss-typings format-check tslint copyrightheaders build:all test test:e2e test:electron",
  "start:electron": "electron drop/electron/extension/bundle/main.bundle.js",
  "test": "jest --projects src/tests/unit",
  "test:e2e": "jest --projects src/tests/end-to-end --runInBand",
  