Sort imports from all files

Add "prettier" script in `package.json` to check if all files are
compliant.

Sort all imports and format all files by running `npm run lint -- --fix`
followed by `npm run prettier -- --write`.

Gitlab #29

Change-Id: Id80402d1344c3bc611f66a46cffeee5f2c375bd8
diff --git a/client/redux/appSlice.ts b/client/redux/appSlice.ts
index 7ddb133..61e73ea 100644
--- a/client/redux/appSlice.ts
+++ b/client/redux/appSlice.ts
@@ -1,4 +1,5 @@
 import { createSlice, PayloadAction } from '@reduxjs/toolkit';
+
 import Account from '../../model/Account';
 
 // Define a type for the slice state