Add non-negative checks

[samuelWilliams99]

Updating means we'll be dropping plutus-extra, as such we drop Naturals, in favor of Integers.
As such, any fields that were changed may need >0 checks onchain.

[samuelWilliams99]

Proposed solution, simple Integer newtype that has an explicit FromData, which checks >=0

[samuelWilliams99]

Need not be as complex as plutus-extra, no need for QQ for example, just an enum instance that'll error, and the Data instances