Support Oauth 2 using JWT User Assertion for SOAP Connections

Please add support for OAuth 2 using JWT User Assertion for SOAP connections. It's currently available for REST connections.

We're using Basic Authentication for connections to Fusion. We considered using Authorization Code but had issues where connections weren't refrreshing the token correctly. As we use Basic Authentication, when we cycle passwords, it becomes problematic as we have around 30 different SOAP connections.

Allowing JWT User Assertion would make it easier to maintain the connections as we could deprecate Basic Authentication and use one authentication method across all the connections to Fusion.

JWT User Assertion is better suited for service-to-service connections compared with Authorization Code as it doesn't require the provide consent step. There's no concept of token refresh which makes it robust.