MINOR: jwe: Add option to enable/disable algorithms or encryption algorithms for...

MINOR: jwe: Add option to enable/disable algorithms or encryption algorithms for jwt_decrypt

Some users of the jwt_decrypt_XXX converters might want to reject JWT
tokens with a specific algorithm or encryption algorithm ("alg" or "enc"
field respectively) in order to avoid weak algorithms for instance.
This could be done from the configuration but would be tedious.

This patch adds the new 'jwt.decrypt_alg_list' and
'jwt.decrypt_enc_list' global options that can be used to define a
subset of accepted algorithms