[Key Vault] Address remaining architect feedback for keys

[mccoyp]

Per the most recent round of feedback for azure-keyvault-keys, we need to take a look at a few more pieces of feedback before the upcoming stable release:

• Move the optional version parameter in KeyClient.release_key into keyword-only arguments
• Try to get update_key_rotation_policy and get_key_rotation_policy to round-trip
  • "If I get a rotation policy - I should be able to pass that back in again, with optional kwargs to overwrite specific attributes."
• Compare key encryption algorithm enums with cryptography names and align where possible
  • cryptography uses aes_key_wrap as the algorithm name and doesn't provide different versions based on number of bytes. For the sake of differentiating our algorithms, and because ckm_rsa_aes_key_wrap is a standard algorithm name in the space, we can keep our KeyExportEncryptionAlgorithm value names. Other algorithms are unchanged and standard
• Make all enums consistently lower-case
• Rename name parameter in KeyClient.get_key_rotation_policy and KeyClient.update_key_rotation_policy to key_name