Need to control consistency between data dictionary member code & viewparams

[eblondel]

In the case a Geoserver viewparam layer is configured (with data parameter property, and a parametrized parameter), there is no control that checks that the parameter name is actually among data dictionary member codes. This creates a discrepancy in OpenFairViewer that inherits parameter names from dictionary (through ISO 19110 structure metadata). Data requests made with viewparams do not work. Some control needs to be set to check that parameter names defined in geoflow match data dictionary member codes .