[i18n] Change Korean language name (#13634)

한글 is name of Korean character not the name of language
한국어 is right name for the ko_KR (South Korea) language code
It's called 조선어 in North Korea but it will require different language code
Ref: https://en.wikipedia.org/wiki/Korean_language

frontend/ui/language.lua

@@ -46,7 +46,7 @@ local Language = {
         ja = "日本語",
         ka = "ქართული",
         kk = "Қазақ",
-        ko_KR = "한글",
+        ko_KR = "한국어",
         ru = "Русский",
         sr = "Српски",
         uk = "Українська",