This diff introduces a test for the `updateSessionItemDeviceToken` method from D5179.
In this test, we will create a `SessionItem` entity and push it to the DynamoDB table. We are checking the default value and updating it using the `updateSessionItemDeviceToken` method and checks the value to become an updated one.
Related Linear task: [[ https://linear.app/comm/issue/ENG-1782 | ENG-1782 ]]