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.
{
    if (request.fHelp || request.params.size() > 1)
        throw std::runtime_error(
            "getblocktemplate ( TemplateRequest )\n"
            "\nIf the request parameters include a 'mode' key, that is used to explicitly select between the default 'template' request or a 'proposal'.\n"
            "It returns data needed to construct a block to work on.\n"
            "For full specification, see BIPs 22, 23, 9, and 145:\n"
            "    https://github.com/bitcoin/bips/blob/master/bip-0022.mediawiki\n"
            "    https://github.com/bitcoin/bips/blob/master/bip-0023.mediawiki\n"
            "    https://github.com/bitcoin/bips/blob/master/bip-0009.mediawiki#getblocktemplate_changes\n"
            "    https://github.com/bitcoin/bips/blob/master/bip-0145.mediawiki\n"
            "\nArguments:\n"
            "1. template_request         (json object, optional) A json object in the following spec\n"
            "     {\n"
            "       \"mode\":\"template\"    (string, optional) This must be set to \"template\", \"proposal\" (see BIP 23), or omitted\n"
            "       \"capabilities\":[     (array, optional) A list of strings\n"
            "           \"support\"          (string) client side supported feature, 'longpoll', 'coinbasetxn', 'coinbasevalue', 'proposal', 'serverlist', 'workid'\n"
            "           ,...\n"
            "       ],\n"
            "       \"rules\":[            (array, optional) A list of strings\n"
            "           \"support\"          (string) client side supported softfork deployment\n"
            "           ,...\n"
            "       ]\n"
            "     }\n"
            "\n"
            "\nResult:\n"
            "{\n"
            "  \"version\" : n,                    (numeric) The preferred block version\n"