Update app widget resize frame UI.

Mock: https://docs.google.com/presentation/d/1UxdDh8EFhPbdRWRwzjbpgL-j02ew4Ew3eG3XBCeoYdo/edit#slide=id.8YyBaHq
Implementation: https://screenshot.googleplex.com/BEFwWBmXXx8xXdS

I will update the drag handles in a follow-up CL since their specs
aren't ready yet.

Test: manual
Bug: 181774580
Change-Id: I19a99e6dbe106754da0fac56a5c2e7eb9eb90cef
diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 3b171c6..da43758 100644
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -52,6 +52,7 @@
 <!-- App Widget resize frame -->
     <dimen name="widget_handle_margin">13dp</dimen>
     <dimen name="resize_frame_background_padding">24dp</dimen>
+    <dimen name="resize_frame_margin">22dp</dimen>
 
 <!-- Fast scroll -->
     <dimen name="fastscroll_track_min_width">6dp</dimen>