Persistent taskbar background is always dark regardless of device theme,
so we should make the icon always light for now.
Test: Manual
Fix: 262837720
Change-Id: I8f66af874e07f68e1943245e9cd49c3b3107915f
1) Fixing missing shadow from shortcut icons
2) Chaning all-apps icon rendering to draw background/foreground separately
This allows us to reuse the bitmap generated for themed icons, instead of
creating a new everytime
Bug: 248308987
Test: Verified on device
Change-Id: Ia3cbefb21a2ce676d6bb2df3d9375d61b5bed61b