3 button nav is laid out correctly.

Updated logic of laying out the 3 nav buttons container. Also updated
placement of the hotseat, so it is not shifted on the phone.

Test: Manual. Fold and unfold felix with and without bubbles. Reboot
the devices and perform the same test.
Fixes: 370773620
Flag: com.android.wm.shell.enable_bubble_bar

Change-Id: I7d5ba51f7ded275f7456a8690d04001b9651f6c5