Implement placeholder icons for remote folder.

Patch 1: Unfinished temporary commit before rebase.
Patch 2: Rebase.
Patch 3:
	1. Add additional RemoteFolderManager hook for drawer adapter setApps().
	2. Replace method arguments in drawer adapter from ArrayList to List,
	which allows us to use Collections.singletonList(), which is more memory
	efficient.
	3. Allow folders to batch remove a subset of their entries.
	4. Remove unused remote flag in ShortcutInfo.
Patch 4: Fix placeholder animation for folder and folder icon.
Patch 5: Remove unused import.
Patch 6: Move app drawer bg color to overlay.

Change-Id: I5ae3b976e2d04dcfbe5ea2e563ef94dcae48b7d4
issue-id: CYNGNOS-1329