The goal of this issue is to run a small selection of functional tests of mldsa-native as part of all.sh. We only want coverage of functional testing on the platforms that we target.

What this means in terms of test coverage:

• Here, we're only testing mldsa-native, the way we build it (compilation options, target platform, compiler flags), but not the way we integrate it (we're not calling any of our integration code).
• We rely on the test coverage in mldsa-native for algorithmic tests, including edge cases.
• Maintainer tests (lint, portability, proofs, etc.) are out of scope here.

TBD: what about constant-time testing?

I'm still investigating, but at this stage I think what we need to do is to run scripts/tests with the right options, similar to the functest action.

Prerequisites: #628