Implement/override equals and hashCode methods in the ServerEncryptionOptions class

We have equals and hashCode  methods in EncryptionOptions object but not (overridden/extended) in ServerEncryptionOptions.

Code is using the EncryptionOptions as the key in the ConcurrentHashMap in the SSLFactory.java.  Hence technically we must have a equals/hashCode override in the ServerEncryptionOptions to account for fields that matter additionally (e.g. outbound_keystore/password). 

We discussed this over the cassandra-dev slack channel and it seems agreeable to make this change.