Pass down whether iterating through tasks in overview is in forward or

backward direction

We are redesigning the alt tab experience and will allow user to iterate
through all the apps in forward and backward directions
Alt+Tab: backward, most recent to least recent
Shift+Alt+Tab: forward, least recent to most recent

Bug: 258854035
Test: manual
Change-Id: Ic274fbb38c73865e18e95a835d5f85ad406616ba