Add generic test if crypt is accepting gensalt and crypt outputs
Add generic test if crypt is accepting gensalt and crypt outputs

Some backends do not test if a hashed password is accepted properly as a
setting, this is a generic place to test it for all backends.

Only default rounds size is tested otherwise the test is taking too long.

besser82/libxcrypt,besser82/libxcrypt,besser82/libxcrypt,besser82/libxcrypt