PROV: Fix the DSA SIGNATURE implementation for better digests handling

PROV: Fix the DSA SIGNATURE implementation for better digests handling

Refactor the DSA SIGNATURE digest setup to be uniform, and to happen
in two places:

1. when given through the digestsign and digestverify inits
2. when given through the set_ctx_params function.

When setting up the digest, we also check that the digest is one of
the officially accepted for DSA.

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/10947)