1) makes the public APIs in cipher-nettle/gcrypt/builtin static,
   and rename them with "nettle/gcrypt/builtin" prefix.

2) introduces cipher framework, including QCryptoCipherDriver
   and new public APIs.

Reviewed-by: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>