Usually in paintmodes one can orbit around the last stroke and also
View > Frame Selected would take the last stroke into account.
This was not the case yet for curves sculptmode.
In order for this to work, there are things (mainly stroke positions) to
update in UnifiedPaintSettings while the stroke happens and this is
what this patch does. There are also two more occasions where
OB_MODE_SCULPT_CURVES has to be taken into account next to
OB_MODE_ALL_PAINT.
NOTE: I can imagine there is a more performant way to do this (and not
getting sample_curves_3d_brush _again_ -- since it might have been used
in the operation already) basically putting this up here to discuss how/
where this would be most appropriate to do instead
NOTE: there a re more places to check still before we can incorporate
OB_MODE_SCULPT_CURVES into OB_MODE_ALL_PAINT all together, so this
patch still has these separate.