Update native contract manifests to be NEP-25 compatible

[AnnaShaleva]

Summary or problem description
#4043 is almost merged which means that we can make native contract manifests follow NEP-25 standard. It's especially important for contracts that have iterators/arrays in method signature, like native Policy (getBlockedAccounts) or native NeoToken (getCommittee, getAllCandidates, getNextBlockValidators, CommitteeChanged event, etc).

Moreover, this change will help us to migrate from handwritten native RPC bindings to auto-generated ones in packages like this: https://github.com/nspcc-dev/neo-go/blob/37f11e43eb8a1409ef0f77070f32cbb51970bec9/pkg/rpcclient/neo/neo.go#L137

Do you have any solution you want to propose?
Include extended NEP-25 types into native contract manifests. Make this upgrade a part of Faun hardfork.

Where in the software does this update applies to?

• Native contracts

[shargon]

Yes, we should follow NEP-25 also in native contracts