[ai] Starter Behavior tree with 1 unit test. more unit tests coming
soon.
This is a base ai tree to build upon and to be included into the
AiActor as it evolves.

QA: there is nothing here for you to test, unit tests only for now.

Change-Id: Ib9479ca9ad669a02ee34856f4bf267e07cbbf523
Merge "[ai] Starter Behavior tree with 1 unit test. more unit tests coming soon. This is a base ai tree to build upon and to be included into the AiActor as it evolves." into unstable