add generic tuple based metarule

[chris-twiner]

Metarules currently use filters against fields in a dataset then generate rules, which is good for generic nullable style tests but not for much else.

What should be added is a list of tuples with a lambda. The arity of the lambda is used to enforce the list has the correct type. Same ordering guarantee is needed, obviously it does so over the tuple.

[chris-twiner]

low prio as it doens't add much over current rule setups