Add a snapshot structure and add commitLineChange table

[xgdyp]

Summary

In This PR,I update a snapshot structure to store each commit code-snapshot.Using this structure,we can get some history message such as who is the previous author in each deleted line,how long do these deleted lines exist and so on.

Does this close any open issues?

related to #1771

Screenshots

This structure is similar to git-import tool in clickhouse repo

Other Information

Any other information that is important to this PR.