[smart_table] refine bucket_table to smart_table

[lightmark]

Description

Personally I researched again around linear hashing, spiral storage and extendible hashing schemes. And still admit the best option for us is linear hashing. So I made a similar change to bucket_table to intelligently set the configurations such as bucket_size and split_threshold.

Also, add two public functions to change these two values at any time as it does not have to be fixed after creation. Those methods give the users more flexibility to adjust their needs on the fly.

Test Plan

cargo test