Move gross single-macro-only "header" into wallet2

This header is stupid and gross and is only used from wallet2.  Remove
it from common/ to contain the damage within wallet2.

simplewallet.cpp includes it just for fun, but never actually uses it,
because why not?

src/common/json_util.h

@@ -1,53 +0,0 @@
-// Copyright (c) 2016-2019, The Monero Project
-// 
-// All rights reserved.
-// 
-// Redistribution and use in source and binary forms, with or without modification, are
-// permitted provided that the following conditions are met:
-// 
-// 1. Redistributions of source code must retain the above copyright notice, this list of
-//    conditions and the following disclaimer.
-// 
-// 2. Redistributions in binary form must reproduce the above copyright notice, this list
-//    of conditions and the following disclaimer in the documentation and/or other
-//    materials provided with the distribution.
-// 
-// 3. Neither the name of the copyright holder nor the names of its contributors may be
-//    used to endorse or promote products derived from this software without specific
-//    prior written permission.
-// 
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
-// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
-// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
-// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
-// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
-// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
-// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
-// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-#pragma once 
-
-#define GET_FIELD_FROM_JSON_RETURN_ON_ERROR(json, name, type, jtype, mandatory, def) \
-  type field_##name = static_cast<type>(def); \
-  bool field_##name##_found = false; \
-  (void)field_##name##_found; \
-  do if (json.HasMember(#name)) \
-  { \
-    if (json[#name].Is##jtype()) \
-    { \
-      field_##name = static_cast<type>(json[#name].Get##jtype()); \
-      field_##name##_found = true; \
-    } \
-    else \
-    { \
-      oxen::log::error(logcat, "Field {} found in JSON, but not {}", #name, #jtype); \
-      return false; \
-    } \
-  } \
-  else if (mandatory) \
-  { \
-    oxen::log::error(logcat, "Field {} not found in JSON", #name); \
-    return false; \
-  } while(0)
-

src/simplewallet/simplewallet.cpp

@@ -75,7 +75,6 @@
 #include "crypto/crypto.h"  // for crypto::secret_key definition
 #include "mnemonics/electrum-words.h"
 #include "rapidjson/document.h"
-#include "common/json_util.h"
 #include "ringct/rctSigs.h"
 #include "multisig/multisig.h"
 #include "wallet/wallet_args.h"

src/wallet/wallet2.cpp

@@ -69,7 +69,6 @@
 #include "rapidjson/document.h"
 #include "rapidjson/writer.h"
 #include "rapidjson/stringbuffer.h"
-#include "common/json_util.h"
 #include "epee/memwipe.h"
 #include "common/base58.h"
 #include "common/combinator.h"
@@ -517,6 +516,30 @@ std::optional<tools::password_container> get_password(const boost::program_optio
   return password_prompter(verify ? tools::wallet2::tr("Enter a new password for the wallet") : tools::wallet2::tr("Wallet password"), verify);
 }
 
+#define GET_FIELD_FROM_JSON_RETURN_ON_ERROR(json, name, type, jtype, mandatory, def) \
+  type field_##name = static_cast<type>(def); \
+  bool field_##name##_found = false; \
+  (void)field_##name##_found; \
+  do if (json.HasMember(#name)) \
+  { \
+    if (json[#name].Is##jtype()) \
+    { \
+      field_##name = static_cast<type>(json[#name].Get##jtype()); \
+      field_##name##_found = true; \
+    } \
+    else \
+    { \
+      oxen::log::error(logcat, "Field {} found in JSON, but not {}", #name, #jtype); \
+      return false; \
+    } \
+  } \
+  else if (mandatory) \
+  { \
+    oxen::log::error(logcat, "Field {} not found in JSON", #name); \
+    return false; \
+  } while(0)
+
+
 std::pair<std::unique_ptr<tools::wallet2>, tools::password_container> generate_from_json(const fs::path& json_file, const boost::program_options::variables_map& vm, bool unattended, const options& opts, const std::function<std::optional<tools::password_container>(const char *, bool)> &password_prompter)
 {
   const bool testnet = command_line::get_arg(vm, opts.testnet);