Focus running task in overview grid

- calculateTaskSize now returns the Rect for focused task
- Introduced calculateGridTaskSize for non-focused task, and translate non-focused tasks to fit the grid
- As Task Rect is now vertically centered, removed ClearAllButton's grid vertical translation
- When ClearAllButton is not shown (e.g. quickswitch), make sure ClearAllButton's scroll won't be used when page snapping. This happens when page scrolls are translated so they're negative.
- Added back ActionsView when task is focused below the TaskView, which become invisible as you scroll
- In Modal state, move the ActionsView down so it won't cover the TaskView

Bug: 175939487
Test: manual
Change-Id: Idfa94a51f856418adc0503cf04211dcb4b1814fe

quickstep/src/com/android/quickstep/fallback/FallbackRecentsStateController.java

@@ -76,7 +76,9 @@ public class FallbackRecentsStateController implements StateHandler<RecentsState
         float clearAllButtonAlpha = state.hasClearAllButton() ? 1 : 0;
         setter.setFloat(mRecentsView.getClearAllButton(), ClearAllButton.VISIBILITY_ALPHA,
                 clearAllButtonAlpha, LINEAR);
-        float overviewButtonAlpha =  state.hasOverviewActions(mActivity) ? 1 : 0;
+        float overviewButtonAlpha =
+                state.hasOverviewActions() && mRecentsView.shouldShowOverviewActionsForState(state)
+                        ? 1 : 0;
         setter.setFloat(mActivity.getActionsView().getVisibilityAlpha(),
                 MultiValueAlpha.VALUE, overviewButtonAlpha, LINEAR);