Creates or Updates the project variables associated with the tenant.

The complete set of project variable values for the tenant; existing values omitted here are deleted. Each item is an object: 'Id' (the existing value's ID when updating; omit when adding), 'OwnerId' (the project ID), 'TemplateId' (the variable template ID), 'Value' (a plain string for non-sensitive values, or {"HasValue": true, "NewValue": "secret"} for sensitive ones), and 'Scope' ({"EnvironmentIds": [...]} limiting the value to those environments; empty applies to all).