Refactor to remove hardcoding of aliases

Unify definition of  aliases in single place.

Make TypeScript configuration file (`tsconfig.json`) source of truth
regarding aliases.

Both webpack (through `vue.config.js`) and ESLint (through
`.eslintrc.js`) now reads the alias configuration from `tsconfig.json`.

tsconfig.json

@@ -29,8 +29,8 @@
       ],
       "@tests/*": [
         "tests/*"
-      ],
-    },
+      ]
+    }
   },
   "include": [
     "src/**/*.ts",