Data Exchange - Corrected processing of parameter read.iges.bspline.continuity

RLN_fix405 (contribution).
- Summary: Corrected processing of parameter read.iges.bspline.continuity set to 0
- Detailed description: When read.iges.bspline.continuity set to 0 (with
Interface_Static::SetCVal()), the BSplineSurface is not enforced to become
periodic if it is closed what is done when it's set to 1. In some cases (e.g.
www.firstcadlibrary.com/seatmotor2.igs, entity 397) this leads to wrong
resulting shape after Shape Healing. Instead of added missing seam the face is
split into a compound of 2 invalid faces.

NOTE: See comments in the code, for consistency between TransferSplineSurface()
and TransferBSplineSurface() the former must have a code to convert to periodic
surfaces, and the latter - to IGESConvGeom for enforcing continuity.
It appeared that OCC IGES converter never enforced surface continuity though it
was expected to. It is up to the OCC team to verify if addition of these calls
will not break regressions.

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Branch OCC22592_IgestobrepSurfaceContinuity is created.