The main structure for the associated offset curve on face feature.
This structure holds an allocated array of UF_CURVE_ocf_string_data_t
structures that have the data assocated with a string, the number of offsets
desired and the offset distances.

This structure also holds a UF_CURVE_ocf_face_data_t pointer that has the
face collector identifier.

The offset method, trim method, span method and the cross boundary method
is also stored in this structure along with the distance, angular and string
tolerances.

This structure has to be allocated and filled with values during create
or has to be allocated and queried from an existing associated offset curves
in face feature, modified to set new offset distances/string/types and then
invoke edit to reflect the changes.