Add a delegate helper for AIDL Delegators

This will check if the binder already has/is a delegator by looking in the
attached objects and attempting to promote the object with the right
objectID.
If the object is already a delegator, it will be unwrapped.
If the object already has a delegator, the delegator will be returned
instead.
If neither of those is true, it will create new delegator that wraps the
binder and return the new delegator.

Test: atest binderUnitTest aidl_integration_test
Bug: 220141324
Change-Id: Ide61342ae5eb30525196384b40c460934146621f