Reimplement test_EclipseIO in Terms of TimeStampUTC

Mostly just to provide a simple overload of the utility function

    ecl_util_make_date

from libecl.  The rest of the test code remains intact.

tests/test_EclipseIO.cpp

@@ -39,6 +39,8 @@
 #include <opm/io/eclipse/EGrid.hpp>
 #include <opm/io/eclipse/ERst.hpp>
 
+#include <opm/common/utility/TimeService.hpp>
+
 #include <algorithm>
 #include <map>
 #include <numeric>
@@ -48,8 +50,6 @@
 
 #include <time.h>
 
-#include <ert/ecl/ecl_util.h>
-
 #include <tests/WorkArea.cpp>
 
 using namespace Opm;
@@ -224,6 +224,12 @@ void checkRestartFile( int timeStepIdx ) {
     }
 }
 
+time_t ecl_util_make_date( const int day, const int month, const int year )
+{
+    const auto ymd = Opm::TimeStampUTC::YMD{ year, month, day };
+    return static_cast<time_t>(asTimeT(Opm::TimeStampUTC{ymd}));
+}
+
 } // Anonymous namespace
 
 BOOST_AUTO_TEST_CASE(EclipseIOIntegration) {