Support state sync

[yun-yeo]

State sync will copy over the iavl store, but it has no idea of the contracts stored under data/wasm. This leads to the following error when querying a contract on a node that was state synced:

Error: Error calling the VM: Cache error: Error opening Wasm file for reading: No such file or directory (os error 2): query wasm contract failed: invalid request

We have same problem with Cosmwasm/wasmd#478.

Requires a solution to cosmos/cosmos-sdk#7340 before we can address this.