AK+Everywhere: Rename String to DeprecatedString

We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)

Userland/DevTools/SQLStudio/ScriptEditor.cpp

@@ -21,7 +21,7 @@ ScriptEditor::ScriptEditor()
     set_ruler_visible(true);
 }
 
-void ScriptEditor::new_script_with_temp_name(String name)
+void ScriptEditor::new_script_with_temp_name(DeprecatedString name)
 {
     set_name(name);
 }