Send display cutout to client via insetsChanged

Since the display cutout is a type of insets and the display cutout can
be obtained from WindowInsets, it makes sense that InsetsState has the
display cutout instance. In this way, we can send the display cutout to
client via W#insetsChanged instead of W#resized.

This can be a step to remove the class of ClientWindowFrames, and can
also be a step to make client compute its window frame locally.

Fix: 175858810
Bug: 161810301
Test: atest WindowAddRemovePerfTest ImeInsetsSourceConsumerTest
            InsetsControllerTest InsetsStateTest ViewRootImplTest
            WindowInsetsControllerTests ActivityRecordTests
            DisplayPolicyLayoutTests LaunchParamsControllerTests
            TaskSnapshotSurfaceTest WindowMetricsActivityTests
            WindowMetricsWindowContextTests WindowMetricsTest
            WindowFrameTests WindowStateTests WmDisplayCutoutTest
Change-Id: I9a930b1d2f7df3cea2b29629b767a4a5f31bca17