Allow assetId to select the asset on addAssetTreasuryAccount

[ohager]

At this moment the transaction full hash is required to identify the token for addAssetTreasuryAccount. It turns out that another call is needed to discover the related transaction reference, although having the assetId already.

it even may happen that there's no transaction hash available when the issuer is a contract - which is ok, as contract tokens do not allow treasury accounts.

So, using assetId is more comfortable (and this operation could be chained then also)