Task: DB Migration script/tools

[i-norden]

We need to write a set of tools for migrating old IAVL state to the new SMT + state storage format. This will be accomplished by performing a JSON dump of the IAVL data, and then loading that dump into the SMT + state storage format as the genesis state for a new Tendermint blockchain.

[tac0turtle]

Hey, this should not require any new tools. We do data dumps to json and back into the tree for upgrades. Modules should handle this internally.

[i-norden]

Closing, see cosmos#9816 and child issues, tracking on zenhub