Allow using display port for window settings

By default display window settings use uniqueId as identifier. For
physical displays it contains information about the display model and
manufacturer, which on some platforms (e.g. Auto) should be ignored
in order to allow replacing displays during repairs/upgrades.

This CL allows configuring use of only port information as
identifier.

Bug: 126594817
Test: DisplayWindowSettingsTests
Change-Id: I3855ca5f5ecd2e33e3eef36933fe5b29ce6b840c