ava: Generate Locale menu automatically (#4243)

Currently in `MenuMainBarView.axaml` we list all available languages and hardcode the language name with the language key.
It's a bit bad beause if we want to add a new language, we have to edit the `csproj` and the `axaml` with the translated language name and the language code.
I've put all translations in their respective locale files, add code into `MainMenuBarView` constructor to generate the menu automatically. Now we just have to edit the `csproj` if we want to add a new language.

Ryujinx.Ava/Assets/Locales/el_GR.json

@@ -1,4 +1,5 @@
 {
+  "Language": "Ελληνικά",
   "MenuBarFileOpenApplet": "Άνοιγμα Applet",
   "MenuBarFileOpenAppletOpenMiiAppletToolTip": "Άνοιγμα του Mii Editor Applet σε Αυτόνομη λειτουργία",
   "SettingsTabInputDirectMouseAccess": "Άμεση Πρόσβαση Ποντικιού",
@@ -610,4 +611,4 @@
   "UserProfilesRecoverLostAccounts": "Recover Lost Accounts",
   "Recover": "Recover",
   "UserProfilesRecoverHeading": "Saves were found for the following accounts"
-}
+}