Fix the computation of default crops to match legacy

Pre multi-crop, the wallpaper is always shown left to right (or right to
left if RTL) and use any additional width for parallax for all screens.

The only exception is for the folded screen of a foldable device: in
that case we always show the center of what's of the unfolded. Since the
logic to do that was in WM and has been deactivated, rewrite this logic
in WallpaperCropper.

Overall, the new system with no suggested crops should work exactly like
the old system. The only difference is that we now set a limit of
maximum parallax (1x the total width of the wallpape for parallax).
This limit shouldn't have real-life effect since the picker never sets a
parallax as high as this.

Flag: ACONFIG com.android.window.flags.multi_crop TEAMFOOD
Bug: 330518320
Test: atest WallpaperCropperTest
Change-Id: I51f77d9e785b9a06b001afd08d480556d4bbde28