Don't add floatingMaskView if it will not fit.

See this screenshot for math explanation: https://screenshot.googleplex.com/9x256x5uk7qNZDg
We use the Y values of the views to determine if the header will be clipped by the
floating mask view.

Also added logs for private space.

bug:343478928
Test manually before: see bug.
after: https://drive.google.com/file/d/1FZXDQG-hV-V3wErVR0-nVCMgjUDk910Z/view?usp=sharing
Flag: com.android.launcher3.enable_private_space

Change-Id: I025e4e62f9ba60e8493d2aceb139d2c4ed6a84dd