* Auto trust new signal identities

from signald doku: when a remote key changes, set trust level to TRUSTED_UNVERIFIED instead of UNTRUSTED 
I find it much more convenient when new identities are automatically recognized as trusted, as the process to do that manually is cumbersome.
Should this the default behavior, or should i add an option to configure this behavior?

* Added option to trust new signal identities

* Using env file

* Renamed variable

* Corrected typo

* Use fully-qualified Ansible module name

* removed option trust_new_keys

Co-authored-by: Slavi Pantaleev <slavi@devture.com>