eknc-engine: dup domains hash table keys
eknc-engine: dup domains hash table keys

We were sticking an app id string that could have been coming
directly from an caller of the engine into the has table. We should
dup the keys to make sure we have our own copy.
https://phabricator.endlessm.com/T14392

endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib