Create or update system variables

[frankgiordano]

Provide a system variable API method to create or update z/OS system variables.

The implementation should support the z/OSMF REST API details and expose the required request/response handling through the SDK.

IBM REST API reference:
https://www.ibm.com/docs/en/zos/3.2.0?topic=services-create-update-system-variables

[Ansita20]

@frankgiordano Sir can you please assign me this issue?

[frankgiordano]

@Ansita20 any update on this?

[Ansita20]

@frankgiordano Yes sir just working on it will raise a pr by tomorrow.

[frankgiordano]

Any update?