Merge #18531: rpc: remove deprecated CRPCCommand constructor

faaf9c58e4 remove CRPCCommand constructor that takes rpcfn_type function pointer (MarcoFalke)
fa19bb2cd8 remove dead rpc code (MarcoFalke)

Pull request description:

  Remove the CRPCCommand arguments, now that they are asserted to be equal and thus redundant

  ### Future work

  > Here or follow up, makes sense to also assert type of returned UniValue?

  Sure, but let's not get ahead of ourselves. I am going to submit any further works as follow-ups, including:

  * Removing all python regex linters on the args, now that RPCMan can be used to generate any output, including the cli.cpp table
  * Auto-formatting and sanity checking the RPCExamples with RPCMan
  * Checking passed-in json in self-check. Removing redundant checks
  * Checking returned json against documentation to avoid regressions or false documentation
  * Compile the RPC documentation at compile-time to ensure it doesn't change at runtime and is completely static

  ### Bugs found

  * The assert identified issue #18607
  * The changes itself fixed bug #19250

ACKs for top commit:
  fjahr:
    tested ACK faaf9c58e4
  promag:
    Tested ACK faaf9c58e4.
  ryanofsky:
    Code review ACK faaf9c58e4. Two obviously good simplifications.

Tree-SHA512: 5de3b440f7b2ed2c3e86655d4f0e2e5df9c67e8ce3c7817d5ea5311d1a38690f2f3e28fab41aad6936be9fc884326d037e5f19e85d4d2fe281474dada13911ee

test/lint/lint-rpc-help.sh

@@ -1,24 +0,0 @@
-#!/usr/bin/env bash
-#
-# Copyright (c) 2018 The Bitcoin Core developers
-# Distributed under the MIT software license, see the accompanying
-# file COPYING or http://www.opensource.org/licenses/mit-license.php.
-#
-# Check that all RPC help texts are generated by RPCHelpMan.
-
-export LC_ALL=C
-
-EXIT_CODE=0
-
-# Assume that all multiline strings passed into a runtime_error are help texts.
-# This is potentially fragile, but the linter is only temporary and can safely
-# be removed early 2019.
-
-non_autogenerated_help=$(grep --perl-regexp --null-data --only-matching 'runtime_error\(\n\s*".*\\n"\n' $(git ls-files -- "*.cpp"))
-if [[ ${non_autogenerated_help} != "" ]]; then
-    echo "Must use RPCHelpMan to generate the help for the following RPC methods:"
-    echo "${non_autogenerated_help}"
-    echo
-    EXIT_CODE=1
-fi
-exit ${EXIT_CODE}