Add a way to turn a regular Parser into an IterParser so that chumsky can be used as a stream transformer

[zesterer]

Example APIs:

Parser::into_iter_parser(self) -> impl IterParser where O: IntoIterator
IterParser::chain(self, impl IterParser) -> impl IterParser
IterParser::repeated(self) -> impl IterParser // TODO: Conflict with <Repeated as Parser>::repeated?