Simple fees: Better error logging when Extras are Missing

The simple fees system validates the fee schedule when it is loaded. When upgrading from existing state, if code changes added a new extra but the fee schedule hasn't been updated yet it will fail saying the extra is missing, but not explain why. May be we can add a validation to the fee schedule validator regarding all extras that should be present, which will run post upgrade. It will show error log if something is missing and we get alerted for it.

Start by locating the simple fees fee schedule validator and the validation path used after upgrading existing state. Trace how missing extras are currently reported. Done means post-upgrade validation logs which required extras are missing and explains the failure clearly.

Written by the indexing model from the issue text.