Parameters are marked required in descriptor file for certian
applications but they are only required if a parent parameter has a
"certain" value. So initial idea was to make all of those parameters
optional from OTB part. So that qgis can work correctly and was a easy
fix. But.. we (me and Antonie) decided not to take that route and
found a better fix.
`OtbParameterChoice` and its wrapper will update optional status of
all sub-parameters depending on the value of a choice parameter.
A test has been added to check this issue and will be available in
next commit.
