refactor: Extract util/exception from util/system

This is a minimal extraction of a single function, but also the only use
of std::exception in util/system.

The background of this commit is an ongoing effort to decouple the
libbitcoinkernel library from the ArgsManager defined in system.h.
Moving the function out of system.h allows including it from a separate
source file without including the ArgsManager definitions from system.h.

src/util/exception.cpp

@@ -0,0 +1,41 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2023 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <util/exception.h>
+
+#include <logging.h>
+#include <tinyformat.h>
+
+#include <exception>
+#include <iostream>
+#include <string>
+#include <typeinfo>
+
+#ifdef WIN32
+#include <windows.h>
+#endif // WIN32
+
+static std::string FormatException(const std::exception* pex, std::string_view thread_name)
+{
+#ifdef WIN32
+    char pszModule[MAX_PATH] = "";
+    GetModuleFileNameA(nullptr, pszModule, sizeof(pszModule));
+#else
+    const char* pszModule = "bitcoin";
+#endif
+    if (pex)
+        return strprintf(
+            "EXCEPTION: %s       \n%s       \n%s in %s       \n", typeid(*pex).name(), pex->what(), pszModule, thread_name);
+    else
+        return strprintf(
+            "UNKNOWN EXCEPTION       \n%s in %s       \n", pszModule, thread_name);
+}
+
+void PrintExceptionContinue(const std::exception* pex, std::string_view thread_name)
+{
+    std::string message = FormatException(pex, thread_name);
+    LogPrintf("\n\n************************\n%s\n", message);
+    tfm::format(std::cerr, "\n\n************************\n%s\n", message);
+}