Add ACTION_SWITCH_DISPLAY_UNFOLD to LatencyTracker

Thanks to this, we will be able to create a dashboard of the time needed to turn on the screen after unfolding the device.

Test: atest DeviceFoldStateProviderTest
Test: atest KeyguardViewMediatorTest
Test: atest UnfoldLatencyTrackerTest
Bug: 209963184
Change-Id: I078be6431e1053bd9658b5756ab2d54f6f28c630