[bug] edi-acknowledgment function should raise exception when a destination is not configured for 997s

[BDQ]

Currently generating 997s requires two Stash keys, if keyfunctional_acknowledgments|this-is-me_another-merchant is defined, then the edi-acknowledgment function will be successful. It will called edi-outbound which will fail if key destinations|this-is-me_another-merchant|997 is undefined, or invalid.

It would be helpful if edi-acknowledgment generates an error if the key destinations|this-is-me_another-merchant|997 is undefined or invalid.