Add support for metadata resolvers to filter returned entity descriptors using predicates.
This will be pretty similar to the filtering support for credential resolvers. See AbstractCriteriaFilteringCredentialResolver.
2 sources of predicates:
1) Criterion's which are also Predicate's. Need to add a new "joining" interface to allow instanceof checks, ala EvaluableCredentialCriterion.
2) Predicates produced by a registry/factory from non-predictate criteria. See EvaluableCredentialCriteriaRegistry.
Also want to optionally allow filtering the whole metadata store via iteration with only predicates, if no "lookup" criteria are supplied or produce a result.
Consider limiting this to BatchMetadataResolver and AbstractBatchMetadataResolver impls only.