aio-witc

Ideas: add option to: ``` joserfc.jwe.decrypt_json(...) ``` example: ``` plaintext=joserfc.jwe.decrypt_json(msg, joserfc.jwk.KeySet([key1]), single_recipient = True) ``` Quickfix: ```python def _perform_decrypt(obj: EncryptionData, registry: JWERegistry) -> None: enc = registry.get_enc(obj.protected["enc"]) iv = obj.bytes_segments["iv"]...