Add additional symmetric key examples

We also support DESede and HMAC keys. Examples generating these types of keys would be helpful. See https://docs.aws.amazon.com/cloudhsm/latest/userguide/java-lib-supported.html#java-keys for supported keys.

Review the existing Java sample applications for symmetric-key generation, then compare them with the supported keys listed in the linked CloudHSM documentation. Add examples for DESede and HMAC keys following the existing examples, and verify that both demonstrate successful key generation.

Written by the indexing model from the issue text.