patch 8.2.4420: menu translations are inconsistent

Problem:    Menu translations are inconsistent.
Solution:   Add a Makefile to convert between encodings. (Ada (Haowen) Yu,
            closes #9801)
diff --git a/runtime/lang/menu_ru.utf-8.vim b/runtime/lang/menu_ru.utf-8.vim
index 20b0b2d..b5e4b79 100644
--- a/runtime/lang/menu_ru.utf-8.vim
+++ b/runtime/lang/menu_ru.utf-8.vim
@@ -1,3 +1,3 @@
 " Menu Translations:	Russian
 
-source <sfile>:p:h/menu_ru_ru.vim
+source <sfile>:p:h/menu_ru_ru.utf-8.vim