refactor: Clio Config (#1593)

Add constraint + parse json into Config
Second part of refactoring Clio Config; First PR found
[here](https://github.com/XRPLF/clio/pull/1544)

Steps that are left to implement:
- Replacing all the places where we fetch config values (by using
config.valueOr/MaybeValue) to instead get it from Config Definition
- Generate markdown file using Clio Config Description

src/util/newconfig/ConfigConstraints.cpp

@@ -0,0 +1,105 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2024, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include "util/newconfig/ConfigConstraints.hpp"
+
+#include "util/newconfig/Error.hpp"
+#include "util/newconfig/Types.hpp"
+
+#include <fmt/core.h>
+
+#include <cstdint>
+#include <optional>
+#include <regex>
+#include <stdexcept>
+#include <string>
+#include <variant>
+
+namespace util::config {
+
+std::optional<Error>
+PortConstraint::checkTypeImpl(Value const& port) const
+{
+    if (!(std::holds_alternative<int64_t>(port) || std::holds_alternative<std::string>(port)))
+        return Error{"Port must be a string or integer"};
+    return std::nullopt;
+}
+
+std::optional<Error>
+PortConstraint::checkValueImpl(Value const& port) const
+{
+    uint32_t p = 0;
+    if (std::holds_alternative<std::string>(port)) {
+        try {
+            p = static_cast<uint32_t>(std::stoi(std::get<std::string>(port)));
+        } catch (std::invalid_argument const& e) {
+            return Error{"Port string must be an integer."};
+        }
+    } else {
+        p = static_cast<uint32_t>(std::get<int64_t>(port));
+    }
+    if (p >= portMin && p <= portMax)
+        return std::nullopt;
+    return Error{"Port does not satisfy the constraint bounds"};
+}
+
+std::optional<Error>
+ValidIPConstraint::checkTypeImpl(Value const& ip) const
+{
+    if (!std::holds_alternative<std::string>(ip))
+        return Error{"Ip value must be a string"};
+    return std::nullopt;
+}
+
+std::optional<Error>
+ValidIPConstraint::checkValueImpl(Value const& ip) const
+{
+    if (std::get<std::string>(ip) == "localhost")
+        return std::nullopt;
+
+    static std::regex const ipv4(
+        R"(^((25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])\.){3}(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])$)"
+    );
+
+    static std::regex const ip_url(
+        R"(^((http|https):\/\/)?((([a-zA-Z0-9-]+\.)+[a-zA-Z]{2,6})|(((25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])\.){3}(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])))(:\d{1,5})?(\/[^\s]*)?$)"
+    );
+    if (std::regex_match(std::get<std::string>(ip), ipv4) || std::regex_match(std::get<std::string>(ip), ip_url))
+        return std::nullopt;
+
+    return Error{"Ip is not a valid ip address"};
+}
+
+std::optional<Error>
+PositiveDouble::checkTypeImpl(Value const& num) const
+{
+    if (!(std::holds_alternative<double>(num) || std::holds_alternative<int64_t>(num)))
+        return Error{"Double number must be of type int or double"};
+    return std::nullopt;
+}
+
+std::optional<Error>
+PositiveDouble::checkValueImpl(Value const& num) const
+{
+    if (std::get<double>(num) >= 0)
+        return std::nullopt;
+    return Error{"Double number must be greater than 0"};
+}
+
+}  // namespace util::config