Add command line tool to dump chain state size

[yzang2019]

Describe your changes and provide context

This PR add a tool to dump a module size by prefix and also tells us total size.

Testing performed to validate your change

Example output:

root@ip-172-31-35-60:/home/ubuntu/sei-db/tools# seidb state-size -d ~/.sei/data/committer.db -m evm --height 82939158
Calculating for module: evm
Module evm total numKeys:4446893, total keySize:103482401, total valueSize:1461642400, totalSize: 1565124801
Module evm prefix breakdown: {
"01": 1848008,
"02": 1847960,
"03": 3970464,
"07": 22294760,
"08": 83968,
"09": 20992,
"0A": 169064,
"0B": 1306833685,
"0D": 50665984,
"0E": 73859936,
"15": 12262,
"16": 16,
"17": 35301
}