Reindex from a block height

[jiqiang90]

Objective:
Since we support historical data, similar as the database snapshot, which mean we could allow user to reindex to specific block height.

Todo:

• use flag --reindex = blockHeight
• validate reindexing blockHeight with metadata (lastProcessedHeight), update metadata once it successful rewinded
• if POI is on, delete mmr to the height(leafIndex), also remove Poi records.
• Remove data in other tables
• put in a tx, if it failed to rewind we still have the original data.

[jamesbayly]

Can we add an additional feature to do a db migration at a specific block height?