Support Istio Explicit protocol selection

[nxd1184]

Currently we would like to achieve mTLS in Kubernetes internal communication so when we use E-STAP with MySQL and MongoDB which are all meshed by Istio then application not able to connect to E-STAP because Istio can not detect protocol.

Istio provide explicit protocol selection manually by the bellowed configuration for service workload

• By the name of the port: name: [-].

• In Kubernetes 1.18+, by the appProtocol field: appProtocol: .

it would be great if we can have an additional appProtocol property in the https://github.com/IBM/Guardium_External_S-TAP/blob/master/charts/estap/templates/estap-service.yaml to support Istio