Update an existing user's information. The 'enterprise_id' and 'is_active' fields cannot be modified directly. The 'is_active' field is computed automatically based on cost center allocations. Use the 'allocations' field to update the user's subsidiary and cost center assignments. Adding allocations will automatically activate the user, and removing all allocations will inactivate them. Note: subsidiary_id, user_manager_id, and cost center ids can be provided as either UUID or internal_id.