Unblock UI thread from updating model.

The model data is loaded from DirectoryResult.cursor, so it makes more sense
to populate all relevant data directly when we generate DirectoryResult
in the background.

Bug: 169449744
Test: atest DocumentsUIGoogleTests
Change-Id: I26557f9fe93ab6cb01599c51f43c0f393e17a2a3
11 files changed