Update scale on TaskView instead for select mode

- Avoid zooming in RecentsView in Select mode, instead zoom in the selected TaskView only to avoid changing RecentsView's scale and pivot, otherwise when doing home gesture in Select mode RecentseView zoom will be distorted
- Set taskModalness on all TaskViews, so they can fade out while entering Select mode, this avoid janky transitionig of non-selected TaskView appearing during hoem gesture
- Keep overviewGridEnabled true until transitioning out of a RecentsView visible state, so showAsGrid() remains true and the Overview grid won't deform midway through animating
- When leaving Select mode to RecentsView invisible state (e.g. Home), leave taskModalness 1 until the last frame so selected TaskView remains zoomed in until RecentsView is invisible

Fix: 322818393
Test: OverviewTaskSelectImageTest
Test: Repeat with combination of default/fallback, live/static tile, handheld/tablet
1) Swipe up from Overview
2) Swipe up from Select to go Home
3) Backc/cross button to exit Select to Overview
Flag: com.android.launcher3.enable_grid_only_overview

Change-Id: I8fec62315cbd404502852654772edb1d695f1ec6