ipa-pki-retrieve-key: request AES encryption (with fallback)
Update the ipa-pki-retrieve-key client to issue a request that
specifies that AES encryption should be used. If the server
responds 404, fall back to a request *without* an algorithm
parameter. This handles both of the possible 404 scenarios:
a) It is an old server that does not support extra Custodia key
parameters;
b) The server supports extra parameters but the key does not exist,
in which case the fallback request will also fail with 404.
Fixes: https://pagure.io/freeipa/issue/8020
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>