in producer, support encryption

[wolfstudy]

Describe alternatives you've considered

Add public encryption key, used by producer to encrypt the data key.

At the time of producer creation, Pulsar client checks if there are keys added to encryptionKeys. If keys are found, a callback getKey(String keyName) is invoked against each key to load the values of the key. Application should implement this callback to return the key in pkcs8 format. If compression is enabled, message is encrypted after compression. If batch messaging is enabled, the batched message is encrypted.

for specific functional descriptions, refer to:

• addEncryptionKey
• cryptoKeyReader
• cryptoFailureAction