Manually apply nav bar insets in DeviceProfile for tablets

- With flexible inset changes in T, taskbar is no longer inseted in getCurrentSizeRange, i.e. DeviceProfile.availableHeight no longer inset nav bar size
- In order for home screen sizes to be calcualted correctly, inset nav bar manually in DeviceProfile

Bug: 215528237
Test: maual in tablet gesture nav and 3 buttons
Change-Id: Ia7d518613eb843f4c45ed77cefc906d7124cb367