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.
{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
    if (request.fHelp || request.params.size() > 5)
        throw std::runtime_error(
            "listunspent ( minconf maxconf  [\"addresses\",...] [include_unsafe] [query_options])\n"
            "\nReturns array of unspent transaction outputs\n"
            "with between minconf and maxconf (inclusive) confirmations.\n"
            "Optionally filter to only include txouts paid to specified addresses.\n"
            "\nArguments:\n"
            "1. minconf          (numeric, optional, default=1) The minimum confirmations to filter\n"
            "2. maxconf          (numeric, optional, default=9999999) The maximum confirmations to filter\n"
            "3. \"addresses\"      (string) A json array of bitcoin addresses to filter\n"
            "    [\n"
            "      \"address\"     (string) bitcoin address\n"
            "      ,...\n"
            "    ]\n"
            "4. include_unsafe (bool, optional, default=true) Include outputs that are not safe to spend\n"
            "                  See description of \"safe\" attribute below.\n"
            "5. query_options    (json, optional) JSON with query options\n"
            "    {\n"