Always focus a task in overview

- Focus first task when applying load plan
- Focus the next task in shorter row when focused task is dismissed, scale the snapshot and translate the task into focused position
- Always show actions view as there is always a focused task. Update scroll alpha when toggling grid enabled
- In fallback recents, take into account that home task will be dismissed when determining rows for the grid, ensuring next focused task won't affect row balancing
- Bring back clearAllShortTotalCompensation as there isn't always a snappedTaskView (e.g. when snapped to ClearAllButton)
- Ensure that getFocusedTaskView is only used when showAsGrid is true

Bug: 187839470
Fixes: 188001858
Fixes: 189057812
Test: manual
Change-Id: I6f31ef469c58fda70d2dd8caa2ee7d8a80c7f03b