Making a gost provider - Add the digests

We add the digests for the provider as wrappers around the routines
designed for ENGINEs.  This is not the most elegant, but it does the
job.

When an algorithm has an OID, it's included in the OSSL_ALGORITHM name
as an aliase.  This is the way to avoid having to register the OIDs in
OpenSSL proper.

test/01-digest.t is modified to test the provider as well.