configure.ac:

* don't default-enable ML-KEM if SHA3/SHAKE are explicitly disabled at user request, or if FIPS <7.
* move ML-KEM flag setup after FIPS setup (like SHA3 and SHAKE flag setup) to allow FIPS overrides.
* remove the unused and misleading "v6-ready" FIPS flavor, and fix v6-dev to get the v6 version triplet.

Author: douzzer