Add new ContextHubTransaction error code

To support synchronous sendMessageToNanoapp failures resulting from
invalid permissions, add a new error code that indicates the transaction
failed due to invalid permissions.

Also adds a recommendation for how apps should behave when interacting
with nanoapps.

Bug: 166846988
Test: compile
Change-Id: I189b387fbcd5c4425a12391e4413519f6befae5e