Support for Mounting Infinispan Secrets

[nmittles]

Feature Request

Problem

When I configure Liberty to use Infinispan as a JCache provider for session caching, I need the username and password credentials located in a secret on the running Infinispan images.

Requested Behavior

I'd like option in the OpenLibertyApplication CRD that would automatically fetch the infinispan secret and mount in the Liberty container. The secret name is example-infinispan-generated-secret by default, and the naming convention is <INFINISPAN_CLUSTER_NAME>-generated-secret
The following PR outlines how Infinispan is configured to be a JCache provider for Liberty docker images: OpenLiberty/ci.docker#155
Also see the following infinispan doc: https://infinispan.org/infinispan-operator/master/operator.html#default_credentials-security