Revert "Revert "Add API for multiple labels in AccesibilityNodeI..."

Revert submission 28486689-revert-27775536-labeledby-SGHWNVGTWT

Reason for revert: fix flag check in AccessibilityNodeInfo parceling

Reverted changes: /q/submissionid:28486689-revert-27775536-labeledby-SGHWNVGTWT

Changes from original CL: the original CL causes hsv to break because
the flag is called in AccesibilityNodeInfo#initFromParcel() when flag
structure is not setup yet. This CL removes the flag check in
AccessibilityNodeInfo writeToParcelNoRecycle, init, initFromParcel. When
the flag is not enabled, the labeledby array is always the same as
default, so corresponding nonDefaultFields bit will not be set, and
parceling and unparceling can still be done correctly.

Flag: android.view.accessibility.support_multiple_labeledby
Test: added cts test, also performed hsv to make sure it is successful.

Change-Id: I53d46b41638982ab95449af0cb680a295b938386