REGTESTS: ssl: add ssl_c_policies test

REGTESTS: ssl: add ssl_c_policies test

Add a VTC covering both modes of ssl_c_policies(): the full list of
Certificate Policies OIDs, and the "-m found" single-OID check (both
a present and an absent OID).

reg-tests/ssl/certs/client1.pem (used by the other ssl_c_* sample
tests) is an X509v1 certificate and carries no extensions at all, so
it cannot be reused here. A dedicated, disposable CA and client
certificate (ca_policies.crt / client_policies.pem) were generated
for this test only, with a Certificate Policies extension containing
0.4.0.1862.1.4 and a filler OID. No personal or production data is
involved, only generic placeholder subject fields consistent with
the other certs in this directory.

Verified locally with vtest (VTest2, "last" tag), alongside
ssl_client_samples.vtc and ssl_client_auth.vtc to confirm no
regressions. checkpatch.pl clean (only the generic, inapplicable
"does MAINTAINERS need updating?" notice, since there is no SSL
maintainer entry).