add export of metadata to ECLGRID2ROFF, ECLINIT2ROFF, ECLRST2ROFF and ECLDIFF2ROFF

For Sim2seis we usually export the eclipse simulation grid and several model parameters (e.g. PORO, SWAT, PRESSURE) to .roff files. This is for visualization in RMS Covisualization. Dynamic parameters (e.g. SWAT) are exported with single dates and 4d diffdates. The issue is that the ECLGRID2ROFF, ECLINIT2ROFF, ECLRST2ROFF and ECLDIFF2ROFF forward models do not produce metadata for SUMO.