Don't save roots of the coins, messages, contract into temporary tables

[xgreenx]

          It seems we don't need a separate `process` step during regenesis, and we can simply iterate over the storage for coins, messages, and contracts, and call the `root` function. It will speed up the most critical part of interaction and slow down the last step that creates a genesis block.

It can be done in the follow up PR.

Originally posted by @xgreenx in #1693 (comment)