Converting action bars to clusters.

ActionBar keyboard navigation logic is now implemented via clusters.
Old implementation using setTouchscreenBlocksFocus and Ctrl+Shift+<
shortcut is removed.

Looking at the code, I can’t rule out existence of all 3 categories
(1) action bars with a nested toolbar, (2) action bars without a
nested toolbar and (3) Toolbars outside of action bars.
Because of this, I set “cluster” attribute both on action bar and
toolbar, and have code to avoid nested clusters in case (1).

Support lib’s action/tool bars aren’t converted, however, they
didn’t regress since Ctrl+Shift+< never worked for them. Will be
done after feature freeze.

Bug: 32151632
Test: Manual checks.
Change-Id: Ieb93980088c0fb385a9bc8a5d218ffc269b94dc5