`FormatMoney(CAmount n)` is not being properly defined for `n = std::numeric_limits<CAmount>::min()`. This is due to an invalid integer negation: the negation of `-9223372036854775808` cannot be represented in type `CAmount` (which has a max value of `9223372036854775807`):

https://github.com/bitcoin/bitcoin/blob/54f812d9d29893c690ae06b84aaeab128186aa36/src/util/moneystr.cpp#L12-L31

FWIW `FormatMoney(-9223372036854775808)` returns `--92233720368.-54775808` when compiled with UBSan (LLVM/Clang, `-fsanitize=undefined`).

Context: https://github.com/bitcoin/bitcoin/pull/20383#discussion_r523250890

It would be nice if `FormatMoney(CAmount n)` was properly defined for all `CAmount n` :)

These are the "expectations of least surprise":

```
BOOST_CHECK_EQUAL(FormatMoney(std::numeric_limits<CAmount>::max()), "92233720368.54775807");       //  9223372036854775807
BOOST_CHECK_EQUAL(FormatMoney(std::numeric_limits<CAmount>::max() - 1), "92233720368.54775806");   //  9223372036854775806
BOOST_CHECK_EQUAL(FormatMoney(std::numeric_limits<CAmount>::max() - 2), "92233720368.54775805");   //  9223372036854775805
BOOST_CHECK_EQUAL(FormatMoney(std::numeric_limits<CAmount>::max() - 3), "92233720368.54775804");   //  9223372036854775804
BOOST_CHECK_EQUAL(FormatMoney(std::numeric_limits<CAmount>::min() + 3), "-92233720368.54775805");  // -9223372036854775805
BOOST_CHECK_EQUAL(FormatMoney(std::numeric_limits<CAmount>::min() + 2), "-92233720368.54775806");  // -9223372036854775806
BOOST_CHECK_EQUAL(FormatMoney(std::numeric_limits<CAmount>::min() + 1), "-92233720368.54775807");  // -9223372036854775807
BOOST_CHECK_EQUAL(FormatMoney(std::numeric_limits<CAmount>::min()), "-92233720368.54775808");      // -9223372036854775808
```

These assertions are _guaranteed_ to hold for all cases above _except_ for the last one.
TestArgsManager testArgs;
    const auto a = std::make_pair("-a", ArgsManager::ALLOW_ANY);
    const auto b = std::make_pair("-b", ArgsManager::ALLOW_ANY);
    const auto ccc = std::make_pair("-ccc", ArgsManager::ALLOW_ANY);
    const auto d = std::make_pair("-d", ArgsManager::ALLOW_ANY);
    const char *argv_test[] = {"-ignored", "-a", "-b", "-ccc=argument", "-ccc=multiple", "f", "-d=e"};
    std::string error;
    LOCK(testArgs.cs_args);
    testArgs.SetupArgs({a, b, ccc, d});
    BOOST_CHECK(testArgs.ParseParameters(0, (char**)argv_test, error));
    BOOST_CHECK(testArgs.m_settings.command_line_options.empty() && testArgs.m_settings.ro_config.empty());
    BOOST_CHECK(testArgs.ParseParameters(1, (char**)argv_test, error));
    BOOST_CHECK(testArgs.m_settings.command_line_options.empty() && testArgs.m_settings.ro_config.empty());
    BOOST_CHECK(testArgs.ParseParameters(7, (char**)argv_test, error));
    
    
    
    BOOST_CHECK(testArgs.m_settings.command_line_options.size() == 3 && testArgs.m_settings.ro_config.empty());
    BOOST_CHECK(testArgs.IsArgSet("-a") && testArgs.IsArgSet("-b") && testArgs.IsArgSet("-ccc")
                && !testArgs.IsArgSet("f") && !testArgs.IsArgSet("-d"));
    BOOST_CHECK(testArgs.m_settings.command_line_options.count("a") && testArgs.m_settings.command_line_options.count("b") && testArgs.m_settings.command_line_options.count("ccc")
                && !testArgs.m_settings.command_line_options.count("f") && !testArgs.m_settings.command_line_options.count("d"));
    BOOST_CHECK(testArgs.m_settings.command_line_options["a"].size() == 1);
    BOOST_CHECK(testArgs.m_settings.command_line_options["a"].front().get_str() == "");
    BOOST_CHECK(testArgs.m_settings.command_line_options["ccc"].size() == 2);
    BOOST_CHECK(testArgs.m_settings.command_line_options["ccc"].front().get_str() == "argument");
    BOOST_CHECK(testArgs.m_settings.command_line_options["ccc"].back().get_str() == "multiple");
    BOOST_CHECK(testArgs.GetArgs("-ccc").size() == 2);
}
BOOST_AUTO_TEST_CASE(util_ParseInvalidParameters)