Data Exchange, Step Import - Adding product attributes to metadata #315

Data Exchange, Step Import - Adding product attributes to metadata #315

Product attributes metadata for step files is now handled during import.
Attribute ReadProductMetadata is added to DESTEP_Parameters.
Method STEPCAFControl_Reader::ReadMetadata() is partially refactored.
Metadata tests for STEP are updated with new data.
Metadata tests for GLTF are updated with new data (since original
metadata in those tests is acquired from STEP files).