The `generate` RPC method:
- was introduced in 2010
- is now only used for testing
- reaches across multiple components (wallet, mining)

I propose we remove the wallet `generate` RPC method and update all tests to use the `generatetoaddress` RPC method. We can do this non-invasively in the test framework by adding a `generate` method to `TestNode` so that the individual tests do not need to be updated. We could also add a `generate` alias to the `generatetoaddress` RPC method.

Doing this removes a wallet->server dependency and simplifies the wallet->server interface (#10973).

I'm opening this issue before implementing in case anyone has objections.
{
        already_witness = true;
        result = id;
        return true;
    }
    bool operator()(const WitnessV0ScriptHash& id)
    {
        already_witness = true;
        result = id;
        return true;
    }
    template<typename T>
    bool operator()(const T& dest) { return false; }
};
static UniValue addwitnessaddress(const JSONRPCRequest& request)