[Satosa][Jwt] Add support for brainpool family curves

[Zicchio]

According to italian documentation, the brainpool family of elliptic curves MUIST be supported.
Currently, we rely on the library cryptojwt for matters concerning jwt verification. Unless I am missing something, cryptiojwt does not support brainpool curves. I tested this hypotesis with the following code snippet, which throws an UnsupportedAlgorithm exception on the last statement. The curve parameters are not random and were generated using library chilkat.

import json
from cryptojwt.jwk.jwk import key_from_jwk_dict

raw = '{"kty":"EC","crv":"brainpoolp256r1","x":"ksK-gc89KSL-7JtWib3mEQr6kgRoreH7Ez2DBfoUTSc","y":"VYb7e6mOg79CaBi2lNEK7dIhrkbU1usBM-DU8uGMXsE","d":"E21xgTxmXD0wbgdXz4C3nwlb4mZxl5vBNkvrQQT8rDY"}'
d = json.loads(raw)

key = key_from_jwk_dict(d)

I am not sure where this issue sits across milestone. Solution might be nontrivial as it implies reviewing project dependencies and how they are wrapped.