NC markers in Eeschema should modify net names in Pcbnew (lp:#1801706)

Original report created by DanHeidel (dan-heidel)

Minor issue, but it would be nice if putting an NC flag on a part pin in
eeschema would then propagate into pcbnew to modify the net names marked on
the part pins there. E.g.:

https://imgur.com/a/X47mcDc

Here, I've got 3 eeschema pins marked with nc flags: 1, 2 and 10. While not
a huge issue, it would be nice in pcbnew, for those same pins to be marked
with an NC prefix, or to simply be named NC rather than
Net-(U2-Pad-[1/2/10]). It would help in keeping track of pins, especially
on high pin count parts.