locales: introduce Internationalization / Locales

* using crate locales

Signed-off-by: Ralf Zerres <ralf.zerres@networkx.de>

locales/main.json

@@ -0,0 +1,15 @@
+{
+  "err.user.not_found": {
+    "fr": "Utilisateur introuvable: $email, $id",
+    "de": "Anwender nicht gefunden: $email, $id",
+    "en": "User not found: $email, $id"
+  },
+  "main.start": {
+    "de": "Programmlogik starten",
+    "en": "Starting program logic"
+  },
+  "parse.arguments": {
+    "de": "Programmargumente prüfen",
+    "en": "Parsing arguments"
+  }
+}