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.
"     \"changeAddress\"          (string, optional, default pool address) The bitcoin address to receive the change\n"
                            "     \"changePosition\"         (numeric, optional, default random) The index of the change output\n"
                            "     \"change_type\"            (string, optional) The output type to use. Only valid if changeAddress is not specified. Options are \"legacy\", \"p2sh-segwit\", and \"bech32\". Default is set by -changetype.\n"
                            "     \"includeWatching\"        (boolean, optional, default false) Also select inputs which are watch only\n"
                            "     \"lockUnspents\"           (boolean, optional, default false) Lock selected unspent outputs\n"
                            "     \"feeRate\"                (numeric, optional, default not set: makes wallet determine the fee) Set a specific fee rate in " + CURRENCY_UNIT + "/kB\n"
                            "     \"subtractFeeFromOutputs\" (array, optional) A json array of integers.\n"
                            "                              The fee will be equally deducted from the amount of each specified output.\n"
                            "                              The outputs are specified by their zero-based index, before any change output is added.\n"
                            "                              Those recipients will receive less bitcoins than you enter in their corresponding amount field.\n"
                            "                              If no outputs are specified here, the sender pays the fee.\n"
                            "                                  [vout_index,...]\n"
                            "     \"replaceable\"            (boolean, optional) Marks this transaction as BIP125 replaceable.\n"
                            "                              Allows this transaction to be replaced by a transaction with higher fees\n"
                            "     \"conf_target\"            (numeric, optional) Confirmation target (in blocks)\n"
                            "     \"estimate_mode\"          (string, optional, default=UNSET) The fee estimate mode, must be one of:\n"
                            "         \"UNSET\"\n"
                            "         \"ECONOMICAL\"\n"
                            "         \"CONSERVATIVE\"\n"
                            "   }\n"
                            "                         for backward compatibility: passing in a true instead of an object will result in {\"includeWatching\":true}\n"
                            "3. iswitness               (boolean, optional) Whether the transaction hex is a serialized witness transaction \n"
                            "                              If iswitness is not present, heuristic tests will be used in decoding\n"
                            "\nResult:\n"
                            "{\n"
                            "  \"hex\":       \"value\", (string)  The resulting raw transaction (hex-encoded string)\n"
                            "  \"fee\":       n,         (numeric) Fee in " + CURRENCY_UNIT + " the resulting transaction pays\n"
                            "  \"changepos\": n          (numeric) The position of the added change output, or -1\n"
                            "}\n"
                            "\nExamples:\n"