Test two situations for AUTH_DO_AUTH_THEN_CIPH:
- when no auth tuple is available
- when the key sequence from LU is marked invalid
Add convenience auth tuple comparison function using stringification.
Add basic MM Authentication test setup, with fake DB access and RAND_bytes().
So far implement simple tests for IO error during DB access and missing auth
entry.
To print the auth action during tests, add struct auth_action_names and
auth_action_str() inline function in auth.[hc].