Get UserPolicyId from server

Description

UserPolicyId is a string which is assigned by the server and shall be reused by the client (https://reference.opcfoundation.org/Core/Part4/v104/docs/7.37).

Code version identification

Current master (b97dad0bf215ddf28af9fe7adc90d4e4a3662fb0)

Current behavior

Using high level client API, user can set this value using an XML file. But user willing to get value from the server needs to implement its own mechanism.

Expected behavior

It would be good to add an API to automatically update the configuration.

Security impact

No cybersecurity impact identified.

Implementation

Add a helper to automatically update the client configuration.