🚨(i18n) add linter to i18n package

We need to add a linter to the i18n package, we are mainly
interested by the jest linting rules so we create
a jest eslint config pluggable our other configs and to the
i18n eslint config.

src/frontend/packages/i18n/jest.config.ts

@@ -1,7 +1,7 @@
 export default {
-  rootDir: "./",
-  testEnvironment: "node",
+  rootDir: './',
+  testEnvironment: 'node',
   transform: {
-    "^.+\\.(ts)$": "ts-jest",
+    '^.+\\.(ts)$': 'ts-jest',
   },
 };