Extract rendering of device item and device group in the list.

This change is required to further split rendering logic from the UI
state generation, so that the new UI theme could be added.

Flag: EXEMPT refactor
Bug: 387570618
Test: atest SystemUiRoboTests:MediaOutputAdapterTest
    atest SystemUIGoogleRoboRNGTests:MediaOutputAdapterScreenshotTest
Change-Id: I87d7aae8db679ee96ad7c6134668daf11d2f76c3