Get rid of unnecessary comphelper::UStringEqual

Change-Id: Ia8718e49f21ccec239b2769eafa6bef90e0e9e40
Remove unused comphelper::UStringIEqual

Change-Id: I3baedaed5bbc942657b1083fc3769cf87622e21c
Combine comphelper::UStringMixEqual, comphelper::TStringMixEqualFunctor

Change-Id: I3ab3777a65fd68f8cbaf17a8e2a989dc4ad7b1cc