Add a new event for display configuration change. This event
will be sent by SF anytime it changes the display config.
Test: Generate DISPLAY_EVENT_CONFIG_CHANGED and observe the log
Bug: 122905403
Change-Id: Ifa473a34d7b313501e5e4e8a67186fb82754fdcd
This CL enables the framework to manage an arbitrary number of physical
displays. It also surfaces physical display IDs, which are stable across
reboots and encode (model, port) information that will be propagated
further up in a follow-up CL.
Bug: 116025192
Test: Boot with more than two displays
Test: Hotplug works with any number of displays
Test: Verify stable display IDs with "dumpsys display"
Change-Id: Idb2eaff66b2e0873be6ad27d337ff18b730d1331
