Do not treat unknown status codes as error

GnuPG keeps adding Status lines. We've discussed that a
whitelist for known status codes makes more sense then to
error out on unkown status lines. This is supposedly safe
and the Way GPA does it since rev. b9efe75a

This fixes edit key commands like certify or setting
ownertrust when GnuPG > 2.1.12 is used.

Backport of GpgME commit: 54314a9c

Merge: None as this has a Regression risk.