Make EntityInfoBuilder method return entity info arrays instead of labels

This is split from the bigger change I9bbbe8055d68b274fa6141eecff4a8d9414f89d9
to make it easier to review.

This change alone may look a bit useless. The idea is to make the existing
protected method getPropertyLabels() more generic. Now it returns the full
EntityInfoBuilder array instead of the labels only. Since we know it contains
only one language it's safe to use reset() to fetch the label. Please note
that these reset() calls will go away in the next patch.

Change-Id: I912882b09d302f8c74b1138b1aa3ab807d19f094
Merge "Make EntityInfoBuilder method return entity info arrays instead of labels"