ITS hub balance tracking should be applied when minter isn't set

[milapsheth]

ITS Hub balance tracking should only be applied when the minter isn't set in the deploy Interchain Token message type. If a minter is set, then the balance invariants can't be preserved since the minter address can mint on the remote chain. This is a fine trade off for custom tokens who want more control. The balance invariant is more so intended for the common use case of deploying a canonical ITS token or a trustless native interchain token to remote chains via the Factory, where the minter isn't set.

Hence, additionally check if minter length is 0 in ITS hub to enable tracking.