Make DisplayCutout.{left,top,right,bottom} be Int's

Given that the insets are computed between composition and layout and
that these should be read during layout rather than composition, it's
better to make them Int's rather than dp's so that people are not
tempted to use them during composition.

Bug: 417960167
Test: presubmits
Flag: com.android.systemui.scene_container
Change-Id: I6394e79938a1fde951baef23805d4abb2effac2b