Avoid ambiguity in "NamedRange_ == NamedRange_"

Without `NamedRange_::operator==`, in the comparison between two
`NamedRange_` instances `nr1` and `nr2` C++20 would not be able to
choose between `(Range_&)nr1 == nr2` and `(Range_&)nr2 == nr1`.

GaudiKernel/include/GaudiKernel/NamedRange.h

@@ -105,6 +105,8 @@ namespace Gaudi {
     /// set the name of the range
     void setName( std::string value ) { m_name = std::move( value ); }
     // ========================================================================
+    using Base::operator==;
+
   private:
     // ========================================================================
     /// the name, associated to the range

GaudiKernel/include/GaudiKernel/Range.h

@@ -223,11 +223,6 @@ namespace Gaudi {
       if ( &right == this ) { return true; } // RETURN
       return right.size() == size() && std::equal( begin(), end(), right.begin() );
     }
-    /// equality with another range type
-    template <class CNT, class IT>
-    bool operator==( const Range_<CNT, IT>& right ) const {
-      return right.size() == size() && std::equal( begin(), end(), right.begin() );
-    }
     /// compare with another container
     template <class ANOTHERCONTAINER>
     bool operator==( const ANOTHERCONTAINER& right ) const {