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() > 3)
        throw std::runtime_error(
            "listreceivedbylabel ( minconf include_empty include_watchonly)\n"
            "\nList received transactions by label.\n"
            "\nArguments:\n"
            "1. minconf           (numeric, optional, default=1) The minimum number of confirmations before payments are included.\n"
            "2. include_empty     (bool, optional, default=false) Whether to include labels that haven't received any payments.\n"
            "3. include_watchonly (bool, optional, default=false) Whether to include watch-only addresses (see 'importaddress').\n"
            "\nResult:\n"
            "[\n"
            "  {\n"
            "    \"involvesWatchonly\" : true,   (bool) Only returned if imported addresses were involved in transaction\n"
            "    \"amount\" : x.xxx,             (numeric) The total amount received by addresses with this label\n"
            "    \"confirmations\" : n,          (numeric) The number of confirmations of the most recent transaction included\n"
            "    \"label\" : \"label\"           (string) The label of the receiving address. The default label is \"\".\n"
            "  }\n"