Add tests for new EVP_CIPHER_CTX IV accessors

Add tests for new EVP_CIPHER_CTX IV accessors

Test that EVP_CIPHER_CTX_get_iv() returns the same IV that was
given at initialization time, and that EVP_CIPHER_CTX_get_iv_state()
returns the expected value after performing an encryption operation
(which will differ from the previous value for CBC and OFB modes),
for various modes of AES.

Do this both for the implicit fetch and explicit fetch paths,
at the cost of a slightly more complicated switch statement.

Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/12233)