EAMxx: bringing nudging in IOP out to the eamxx nudging module

[mahf708]

In #6787, IOP is made its own atm proc. We should consider abstracting out redundant impls from IOP to existing infra. As a first step, allow IOP cases to be nudged from the eamxx/nudging proc. This will require some code edits and more flexibility in the eamxx/nudging.