[breaking] dialect: re-map (not) exists operators to subquery builder

[esatterwhite]

The list builder was generating incorrect sql for the exits and not exists operators. This adds a sub query build for these two cases to render the sql accurately.

These two operators now use the subquery builder rather than the list operator

Semver: major Ref: #11

[jails]

Fantastic :100: !! By the way why using the array syntax ':exists': [subquery] instead of simply ':exists': subquery ? not sure exists can handle multiple queries.

[esatterwhite]

Ya, thats fair. will remove

[jails]

Perfect ! Thank you :+1: