iSP-393 -Patch request for PDI-10242 - CSV Input Step - Unable to pass file encoding as parameter (5.0)

What was done :
1) changed the way get fields button initializes the process
Merge pull request #179 from kolinus/SP-393-rebased

SP-393 -Patch request for PDI-10242 - CSV Input Step - Unable to pass file encoding as parameter (5.0)