Center layout of nav inflator to wrap content to tap other buttons

When you hold home button (that is within the center group) you cannot
tap any other nav button because home button and its parent consumes it.
Make it wrap the content so that the back and recents button can be
pressed while holding home. This is used to unpin better for quick step
enabled.

Test: manual - hold home and tap back/recents, easier when pinned
Change-Id: I73b326235885e5e29c07b9540b4311a0c820ff78
Fixes: 77522636
Fixes: 73175803