Move all the window layout logic to WindowLayout

This CL removes redundant layout logic in computeFrame and moves all the
window layout logic to WindowLayout. We don't need mContainingFrame in
WindowFrames anymore.

The goal in the future is to let the client side to invoke
WindowLayout#computeWindowFrames, and then send the frames to the
server. The server will only use the method to layout the insets source
windows.

Bug: 161810301
Bug: 175858823
Test: atest DisplayPolicyLayoutTests WindowLayoutTests
            DialogFrameTests ManifestLayoutTests ToastWindowTest
Change-Id: I91aa8051970cb8f30f4c13849a4db79b16182075