[cryptotest] Test harness for SPHINCS+ verify operation w/ SHAKE-256

[RyanTorok]

This PR is a follow-up to #21680. Adds a test harness for SPHINCS+ verify operation tests w/ SHAKE-256 in the style of the test harnesses for the algorithms in cryptolib. Structurally, the test harness has a lot in common with the ECDSA harness in #21113 and #20853, except that there is no elliptic curve parameter.

The dependency on #22953 exists because this PR switches the test vectors to use the consistent-basew version of SPHINCS+.

~Dependent on #21680~ Dependent on #22953