Todos

[abdulmth]

1. Add test vectors with decoys from the specs comment
2. State in the Hasher trait, that users are expected to only implement Hashers whose alg_name returns a value from the list mentioned in the spec comment.
3. Replace all occurences of _sd_alg with a constant defined somewhere comment.
4. Use constant salt size comment.
5. Implement try_from_serializable instead of impl TryFrom<Value> for SdObjectEncoder comment
6. Remove returned disclosures from decoys comment
7. Generate > 128 random bytes first, then encode them to base64 later to get a string comment
8. Fix random string generation by generating128 bits of cryptographically secure random data and then base64url-encode them. comment
9. improve digest_b64_url_only_ascii comment
10. Fix unnecessary ASCII filtering comment
11. Feature gate sha hasher

[abdulmth]

done in #4