codemaker,editeng: prefer passing OUString by reference

Change-Id: If3e2dd3905cc33f1e7fc9fbfbb9f2bb49a756a34
filter,formula: prefer passing OUString by reference

Change-Id: I332f1a593853283b72ecf4dfd82b36cc091661b4
sal,toolkit,unotools: prefer passing OUString by reference

Change-Id: Ie62a59fd9ff3d6f6a34240fd562fbc91a143bf3a
oox: prefer passing OUString by reference

Change-Id: Iace276878e7ae668bba5bb6e36af1e5d5d72d6cb