Add SASL SCRAM-SHA-256 support.

* lisp/net/sasl.el (sasl-mechanisms): Add SCRAM-SHA-256.
(sasl-mechanism-alist): Ditto.
* lisp/net/sasl-scram-sha256.el: New file.
* tests/lisp/net/sasl-scram-rfc-tests.el (sasl-scram-sha-256-test):
New function.
1 job for master in 54 minutes and 22 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #4771
test-all

00:54:22