Fix Scribe translations by using multiple_localization package

Even if all keys were translated, Scribe UI was always in default
language.

In short, it is not possible to load multiple localization delegates
with different .arb files. But we need these translations to be
located in a separate file because in the future we will move Scribe
in a separate module.

See
https://github.com/Innim/flutter_multiple_localization for more
explanation.

scribe/pubspec.lock

@@ -798,6 +798,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.0.6"
+  multiple_localization:
+    dependency: "direct main"
+    description:
+      name: multiple_localization
+      sha256: "29c97a3fbf4d067ea5a63df1995465ea81ef28e2c817d9d0871983e50f4fd3f0"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.6.0"
   objective_c:
     dependency: transitive
     description: