crypto/internal/fips140test: add KAS-ECC-SSC ACVP tests

crypto/internal/fips140test: add KAS-ECC-SSC ACVP tests

Adds ACVP test coverage for the Sp800-56Ar3 KAS-ECC-SSC algorithm based
on the NIST spec:

  https://pages.nist.gov/ACVP/draft-hammett-acvp-kas-ssc-ecc.html

There's no acvp_test.config.json update for this algorithm as one test
type type requires random key generation and can't be separated from the
test type that doesn't, making it a bad fit for static data testing.

Updates #69642

Change-Id: I3b6538fad1c1e5c8b14b638ff3b933f11e98f75a
Reviewed-on: https://go-review.googlesource.com/c/go/+/637916
Reviewed-by: Roland Shoemaker <roland@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>