Add an empty row on grid when importing "empty" csv

If user import csv file in DMN scenario, which contains only header, then the Background contains no rows see image.png

Steps to reproduce :

1. Import Driver Suspension Rules.dmn
2. Import DmnAssert.scesim
3. In scesim file import DmnAssert.scesim.csv

Expected: Grid with the cells state the same as after initialization
Actual: user has no rows to add a value