Adding French Translation

Added french to usable language in the language.js file

Juste changed a line in french.js for ui tweaker entry to reflect its meant to customise the Ui .

NUXT/plugins/language.js

@@ -1,6 +1,7 @@
 const packs = {
   bulgarian: require('./languages/bulgarian'),
   english: require('./languages/english'),
+  french: require('./languages/french'),
   german: require('./languages/german'),
   italian: require('./languages/italian'),
   macedonian:  require('./languages/macedonian'),

NUXT/plugins/languages/french.js

@@ -16,7 +16,7 @@ module.exports = {
     general: "Général",
     theme: "Thème",
     player: "Lecteur",
-    uitweaker: "Interface",
+    uitweaker: "Personnalisation d'Interface",
     startupoptions: "Options de démarrage",
     plugins: "Plugins",
     updates: "Mises à jour",