feat: add tool to migrate stores for fastnode

[forcodedancing]

Description

Add tool to migrate the stores, in mutli root store, from IAVL stores to DB stores.

Rationale

For switch a full node to a fast node.

Example

./build/bin/gnfd migrate-store --home ./deployment/localup/.local/dataseed1 

Changes

Notable changes:

• new command

[j75689]

There are risks with OOM I think, maybe can consider adding a BatchLimit and do WriteSync in the loop

[forcodedancing]

I agree. I had tried to call WriteSync for batches. However, there are some issues, I will figure out it.

[forcodedancing]

// WriteSync implements Batch.
func (b *goLevelDBBatch) WriteSync() error {
	return b.write(true)
}

func (b *goLevelDBBatch) write(sync bool) error {
	if b.batch == nil {
		return errBatchClosed
	}
	err := b.db.db.Write(b.batch, &opt.WriteOptions{Sync: sync})
	if err != nil {
		return err
	}
	// Make sure batch cannot be used afterwards. Callers should still call Close(), for errors.
	return b.Close()
}

The batch implementation is wired. After write it will be closed.

At the same time, Batch is rarely used in the project. I will remove the use of batch as well.