feat request: support Google MemoryStore in-transit encryption

[jasonschroeder-sfdc]

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Buildfarm works fine with a Google Cloud Platform Memorystore configured in cluster mode, including password-based auth.

What doesn't work is the in-transit encryption, where GCP provides a Certificate Authority to encrypt traffic.

https://cloud.google.com/memorystore/docs/redis/about-in-transit-encryption

Work to be done:

• add something to the Backplane configuration to find the CA certs
• pass this to the Jedis constructor in JedisClusterFactory

[jasonschroeder-sfdc]

Looking at https://sterl.org/2016/07/self-signed-certificate-java-sslcontext-and-sslsocketfactory/ as a good example to set up the SSLSocketFactory

[jasonschroeder-sfdc]

Got stuck here :( https://github.com/redis/jedis/issues/3837