Add queryNamedWith and foldNamedWith

[tmcl]

queryWith and queryWith_ take an explicit RowParser, but there is no counterpart for named parameters.
This adds the missing *With variants for named parameters, following the same pattern as the existing queryWith/queryWith_ functions.

[jchia]

For consistency, what about also adding foldWith and foldWith_?

[tmcl]

It's true it ends up with a bit of a gap without them. Here they are.