Add rotation field to ThumbnailData for task snapshots

Add the rotation a task was in when its snapshot
is taken. This is used by launcher to know which
way to orient the bitmap when performing quickswitch

fixes: 143892437
Test: Test: With launcher in portrait
* Thumbnail in reverse portrait,
landscape, seascape, normal
With launcher in landscape
* Thumbnail in seascape, normal,
reverse portrait, landscape
With launcher in seascape
* Thumbnail in seascape, normal,
reverse portrait, landscape

Change-Id: Iaf32341d0db1fc023c29676e0d365eee03b98959