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() != 2)
        throw std::runtime_error(
            "setlabel \"address\" \"label\"\n"
            "\nSets the label associated with the given address.\n"
            "\nArguments:\n"
            "1. \"address\"         (string, required) The bitcoin address to be associated with a label.\n"
            "2. \"label\"           (string, required) The label to assign to the address.\n"
            "\nExamples:\n"
            + HelpExampleCli("setlabel", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\" \"tabby\"")
            + HelpExampleRpc("setlabel", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\", \"tabby\"")
        );
    LOCK(pwallet->cs_wallet);
    CTxDestination dest = DecodeDestination(request.params[0].get_str());