Ensure `.and` can only be used when the left side is a bool expression
Ensure `.and` can only be used when the left side is a bool expression

While the actual node is dumber and doesn't care about the types of
either side (so it can be used w/ `Between`), I still want the user
facing DSL to be as strict as possible.

sgrif/diesel,mcasper/diesel,cascalheira/diesel,mcasper/diesel,diesel-rs/diesel,SoftwareWarlock/diesel,sgrif/diesel,cascalheira/diesel,tohou/diesel,SoftwareWarlock/diesel,diesel-rs/diesel,tohou/diesel