Simplify the parameter of getWindowInsets

Since getLayoutHint is removed, it no longer needs a window
layout parameter to get insets. And because the param is empty,
enforceInsetsPolicyForTarget was also no-op.

This can reduce write/read fifty unused fields to parcel, and
ensure the insets sources are only copied once to the output.

Bug: 151908239
Test: atest android.view.WindowMetricsTest
Change-Id: I086aa229a9e2468b0c2c302deabe2234abd90080