Send size-compat scale to the client

The client computes the window frame on its own in ViewRootImpl#setView.
However, the bounds obtained from WindowConfiguration is not size-
compatible, which makes legacy apps produce wrong frames. The frame is
larger than expected, so when computing WindowInsets with size-
compatible InsetsState, the window cannot receive insets.

Although the client will receive the correct window frame from relayout,
but the first WindowInsets has been dispatched before that.

This CL sends the size-compat scale to the client, so the client can use
the correct WindowConfiguration to compute frames.

This is also a step to enable the client to perform local window layout.

Bug: 237749017
Bug: 161810301
Bug: 175861127
Test: atest StartingSurfaceDrawerTests WindowAddRemovePerfTest
      ActivityRecordTests WindowManagerServiceTests
Change-Id: I6b23901f4b1f009444c04da7e078ea971a386ad7