fix: Avoid storing the position in primitives::uncons_while
fix: Avoid storing the position in primitives::uncons_while

All current `RangeStream`'s never return an error on uncons_while so they will not change behavior and as long as `RangeStream`s don't update their positions if they fail there will be no change in behavior anyway.

Marwes/combine,Marwes/parser-combinators,Marwes/combine,tempbottle/combine