Add DataLayer wallet capability to create_new_wallet RPC

[danieljperry]

It would be nice to have the ability to use an RPC to create a new, empty DataLayer wallet. Currently, a DataLayer wallet can only be created when a user creates a new store or subscribes to an existing one. The benefactors of this feature would be new users of a DataLayer subscription service who are just getting started and don't yet know to which stores they can subscribe. Note that there is a workaround (create a dummy store and have people subscribe to it in order to create a DataLayer wallet).

In addition, this feature would be nice for consistency. The create_new_wallet wallet RPC allows you to create empty wallets of various types (cat, did, dao, nft) but not datalayer.

The data_layer_wallet code has a method for creating a DataLayer wallet, but there currently isn't an RPC that calls it (AFAIK).