Load direct-share icons asynchronously

Move direct-share icons loading off the main thread in the same way
we're loding A-Z icons.

Test: Manual testing with rotatin and screen locking, artificially
delaying image loading, debug logging for potential event loops.
Test: atest ChooserListAdapterTest
Fix: 215699869
Change-Id: I97e3383a74bb4ef795099fe55cae9fc5aed2b790

Change-Id: I3b110447d4cf2ab94e663c2684cd2cce4968d4ca