Feature: Support block-cache to avoid frequent IO requests.

[Little-Wallace]

Feature Description

In order to complete the prototype of the database as quickly as possible, I did not design the cache before, which would cause all requests to directly access the disk data. I hope a rocksdb-like block-cache but if anyone else has a better opinion, I'll gladly accept it.

Module

• add a new module cache.
• table. Create the cache object in table_factory and send it to every TableReader.