Support insets on secondary displays

Indroduced DisplayFrames object to track frames used to calculate
window insets per display vs. at a global level in PhoneWindowManager.

Bug: 64148922
Test: bit FrameworksServicesTests:com.android.server.wm.ScreenDecorWindowTests
Test: go/wm-smoke
Change-Id: I4a668d6c2dd0bfa666cb6acecf663cf83545ea87