Fix overview cmd launching wrong task in landscape

Previously we used the bottom most view in recents list to launch the
recent task when the user pressed the overview button. However, if
the user is in landscape and scrolls up so the bottom view is not
attached, pressing overview command will launch whatever the bottom task
is visually which is incorrect. Instead, we get the actual task from the
model to launch and only use the "view => app" animation if the view for
that task is attached. If it isn't, we use the basic animation.

Bug: 130735711
Test: Go to landscape, scroll up, hit command, launches correct task
Change-Id: Idff88054443259e917bbec1b47d78efbb1544283