Implement user allowlist flows

For 0.17, we'll need to implement the network allowlists flows explained [here](https://github.com/0xMiden/node/issues/2576). To recap: When a user wants to register an account, they must do so through a one-time pin code. After this, the account gets allowlisted and transactions for this account will get accepted on the transaction/user batch endpoints. In the client we'll need to support the following:

- RPC client should have these register/query commands and they should be exposed to the user
- We may want to integrate the endpoints in the following way:
- On any API that inserts new accounts exclusively (`add_account`, etc.), we can first check through RPC whether the account is allowlisted on the network. If it is not, we should error explaining that the account first needs to get registered, and this requires a pin code. Importing accounts from the network should obviously be fine, and when importing from files we could also enforce validation against the network or at least checking that it's allowlisted.
- Alternatively here we could instrument all APIs that create accounts to take the pin code as a parameter and use it to register the account.
- EDIT: We may also want to add this to the CLI, and prompt the user to enter the pin code when they want to create an account

I believe the functionality will be relatively short-lived and so we probably don't need to spend a lot of energy thinking about more long-term strategies for this feature.

The issue references a design document at https://github.com/0xMiden/node/issues/2576. Start by reading that to understand the allowlist flow. The work involves the RPC client, account creation APIs, and possibly the CLI. Look for existing account creation endpoints and RPC command structures. 'Done' means the client can register an account with a pin, check allowlist status, and appropriately error or prompt during account creation.

Vom Indexierungsmodell aus dem Issue-Text verfasst.