Specialize the SCRAM-SHA-1 mechanism, to provide a new mechanism supporting SCRAM-SHA-256.
This may require adding some additional customization points to the SCRAM-SHA-1 templates.
The server will need to expose, and the mechanism will need to consume, a scramSHA256IterationCount setParameter.
The SCRAM-SHA-256 mechanism will need to consume ICU4C for SASLPrep normalization of usernames and passwords.
The SCRAM-SHA-1 unittests should be generalized to test both mechanisms.