Fix bug 1584489: Remove fr and es from supported languages (#1399)

Also: Add l10n.toml file to use to check l10n status and quality

frontend/src/core/l10n/index.js

@@ -15,4 +15,4 @@ export const NAME: string = 'l10n';
 
 // List of available locales for the UI.
 // Use to choose which locale files to download.
-export const AVAILABLE_LOCALES: Array<string> = ['fr', 'es', 'en-US'];
+export const AVAILABLE_LOCALES: Array<string> = ['en-US'];

l10n.toml

@@ -0,0 +1,10 @@
+basepath = "."
+
+locales = [
+    "es",
+    "fr",
+]
+
+[[paths]]
+    reference = "frontend/public/static/locale/en-US/*.ftl"
+    l10n = "frontend/public/static/locale/{locale}/*.ftl"