Add Secure support in Federated uReplicator

[prat0318]

This PR adds the following features:

• Ability to plug in a cluster as secure for SRC but non-secure for DEST and vice-versa
• A separate secure.kafka.cluster.servers.<cluster> is added to get the secure cluster host/port.

Following three properties are added to the worker:

secure_feature_enabled (Default: False) : This feature will only kick in when this property is set to True in the Worker Config.
secure_clusters_set (Default: nil) : If a subset of all clusters are targeted as secure, this set determines those secure clusters.
secure_config (Default: secure.properties) : If 1st property is true, and cluster is included as per set in the 2nd property, the properties mentioned in `secure_config` will be included in the producer/consumer configs.

[CLAassistant]

All committers have signed the CLA.

[yangy0000]

LGTM