Wish: FilletSrfToRail with constant radius

testfilletsrfcrv and TestFilletSrfToRail have graduated to normal commands, _FilletSrfCrv and _FilletSrfToRail, respectively, in the WIP. I leaned about them from VSR end of Life- - #361 by Gijs

FilletSrfCrv requires 2 geometric input:

  1. Surface near a curve
  2. Curve near the surface selection point. The curve should be near, but not on, the surface.

Similar to FilletSrf, FilletSrfCrv output has a constant section.
The general solution for FilletSrfToRail is a variable fillet.