Update drag and drop visualizations

=> Remove the bitmap-based icon outline
=> Add simple cell based location preview of drop location
=> Round corners of page outlines
=> Get rid of page background for focused page
=> Update colors to use system accent color

Bug: 185163323

Test: manual

Change-Id: Id604c59201536967e25236f305eeeb0aafc9c022
diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 51dddab..08da632 100644
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -166,7 +166,7 @@
 
     <dimen name="drag_flingToDeleteMinVelocity">-1500dp</dimen>
 
-    <dimen name="spring_loaded_panel_border">1dp</dimen>
+    <dimen name="spring_loaded_panel_border">2dp</dimen>
     <dimen name="keyboard_drag_stroke_width">4dp</dimen>
 
 <!-- Folders -->
@@ -298,4 +298,8 @@
     <dimen name="task_thumbnail_icon_size_grid">0dp</dimen>
     <dimen name="overview_task_margin">0dp</dimen>
 
+<!-- Workspace grid visualization parameters -->
+    <dimen name="grid_visualization_rounding_radius">28dp</dimen>
+    <dimen name="grid_visualization_cell_spacing">6dp</dimen>
+
 </resources>