Coordinator shouldn't implement IEncryptionAuthorizer logic

[cygnusv]

Currently, Coordinator includes a function isEncryptionAuthorized that calls the access controller and nodes use it. Instead, we should remove this function, and nodes should be capable of resolving the access controller contract and contact it directly

[cygnusv]

Current decision is:

• Leave this method in the contract, with a deprecation note.
• Remove related endpoints in the nucypher client and include this change in the next release
• Remove contract method only when we have assurance that the vast majority of nodes are running the next release or newer, and/or there's a mechanism to penalize nodes running outdated versions (see [WIP] Peer Snitching Contract #248)