Backport 2.28: Show unmet dependencies by name in test_suite_xxx -v

[gilles-peskine-arm]

When running a test suite verbosely, if a test case is skipped due to a compile-time dependency on the test case, show e.g. Unmet dependencies: PSA_WANT_ALG_XTS PSA_WANT_ECC_FAMILY_TWISTED_EDWARDS rather than Unmet dependencies: 42 19.

Ideally we'd also do that for function and suite dependencies. But that's less useful and would take additional work, so I don't intend to do it today.

PR checklist

Please tick as appropriate and edit the reasons (e.g.: "backport: not needed because this is a new feature")

• [x] changelog no (test stuff only)
• [ ] backport of TODO
• [x] tests yes

[gilles-peskine-arm]

I have a fix ready to push for the pylint failure (holding off to prioritize release jobs on the CI).