style(format code): add prettier

package.json

@@ -145,5 +145,8 @@
     "presets": [
       "react-app"
     ]
+  },
+  "devDependencies": {
+    "prettier": "1.19.1"
   }
 }

yarn.lock

@@ -8382,6 +8382,11 @@ prelude-ls@~1.1.2:
   resolved "https://registry.yarnpkg.com/prelude-ls/-/prelude-ls-1.1.2.tgz#21932a549f5e52ffd9a827f570e04be62a97da54"
   integrity sha1-IZMqVJ9eUv/ZqCf1cOBL5iqX2lQ=
 
+prettier@1.19.1:
+  version "1.19.1"
+  resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.19.1.tgz#f7d7f5ff8a9cd872a7be4ca142095956a60797cb"
+  integrity sha512-s7PoyDv/II1ObgQunCbB9PdLmUcBZcnWOcxDh7O0N/UwDEsHyqkW+Qh28jW+mVuCdx7gLB0BotYI1Y6uI9iyew==
+
 pretty-bytes@^5.1.0:
   version "5.1.0"
   resolved "https://registry.yarnpkg.com/pretty-bytes/-/pretty-bytes-5.1.0.tgz#6237ecfbdc6525beaef4de722cc60a58ae0e6c6d"