Merge "setAdjacentTaskFragments for paired TaskFragment" into sc-v2-dev am: 1a9c49f643 am: dfa4393321

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15404414

Change-Id: Ib6d9c136e3be0e665fcbfe61a110f7b650925d82