Custom height db dump

[grarco]

The implementation of the dump-db command provided in #1184 only allows dumping the state of the last block height. It would be useful to accept a --height argument to specify which state should be dumped.

To obtain such state we could reapply the diff subkeys recursively to their corresponding subspace key. This operation should start either from the last block or the first one depending on which one is closer to the desired height, to reduce the number of operations to run. In case the starting point was the first block we should also make sure to load any state from the genesis file.

For the diffs targeting the desired height we can immediately apply that diff without the need to reapply all of them.

Mind that the read_subspace_val_with_height does not work in this case as it applies a similar but different logic.

[grarco]

Actually, given #1466, read_subspace_val_with_height is indeed what we want