Prefer signing_algorithm and digest_algorithm over sign_alg and digest_alg
Prefer signing_algorithm and digest_algorithm over sign_alg and digest_alg

Continuing the deprecation of saml2 frontend sign_alg and digest_alg
configuration options (see, 04850eeb395b3f19c70507aa1e03201ff787b6a3).

The values of the new options should be preferred when set. Otherwise,
we fall back to the deprecate options.

Notice that the new configuration options expect the algothim
identifier, not an internal symbol.

Signed-off-by: Ivan Kanakarakis <f60d6943d72436645c4304926eeeac2718a1142c@gmail.com>

SUNET/SATOSA,SUNET/SATOSA,its-dirg/SATOSA