Redesign homepage layout for two-pane mode.

In a high level, I created two versions of app bar layout.
One for single pane design, another for two-pane design.

Then, app initilizes two different layouts in the beginning,
we simply show/hide one version while app is receiving the
configuration changes update.

Test: Rebuilt apk and observed the screen.
Bug: 195293058
Change-Id: Icd19ea02ab1be4e964701b22ae9e20c9e00d3c0d