Fix folder path truncation in filemanager with utf8 chars (#3599)

frontend/util.lua

@@ -129,6 +129,13 @@ function util.lastIndexOf(string, ch)
     if i == nil then return -1 else return i - 1 end
 end
 
+--- Reverse the individual greater-than-single-byte characters
+-- @string string to reverse
+-- Taken from https://github.com/blitmap/lua-utf8-simple#utf8reverses
+function util.utf8Reverse(text)
+    text = text:gsub('[%z\1-\127\194-\244][\128-\191]*', function (c) return #c > 1 and c:reverse() end)
+    return text:reverse()
+end
 
 --- Splits string into a list of UTF-8 characters.
 ---- @string text the string to be split.