testdesc: Report each unsupported test individually
Previously, if a stanza in d/tests/control had unknown fields or unsupported restrictions, we would log that for the first test in the stanza (only), for example:
Tests: one two
Restrictions: needs-root
Tests: foo bar
Restrictions: needs-more-cowbell
would be logged as
one SKIP Test needs root on testbed which is not available
foo SKIP unknown restriction needs-more-cowbell
This is sufficiently confusing that it led me to file an invalid bug report about autopkgtest not supporting space-separated tests. If we report the Unsupported exception for each test-case, it becomes clearer what's really going on:
one SKIP Test needs root on testbed which is not available
two SKIP Test needs root on testbed which is not available
foo SKIP unknown restriction needs-more-cowbell
bar SKIP unknown restriction needs-more-cowbell
Closes: #851232