Adds additional folder label states (UNLABELED & EMPTY_LABEL)

UNLABELED -> title==null and EMPTY_LABEL -> title=="". When adding new items for the folder if the folder is in UNLABELED state, auto-labeling will be enabled.
This change also addresses auto-labeling issue due to false edit from UNLABELED to EMPTY.

Bug: 159164315

Change-Id: Ia17cd27b4afb60420dc15c544f544061fc46ad33
6 files changed