[NEW]Fill the API/functionality gap of KVDK::Hash and Redis::Hash

[Chen Cheng]

The problem/use-case that the feature addresses

The Redis::List commands require KVDK::Hash provide more functions.

Description of the feature

E.g.
Redis::Hash::HLEN ---> KVDK returns the length of the Hash
Redis::Hash::HKEYS ---> KVDK returns all field names in the hash stored at key.
Redis::Hash::HRANDFIELD ---> KVDK returns a random field from the hash value stored at key.
Redis::Hash:: HVALS ---> KVDK returns all values in the hash stored at key.