`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.
{
    BOOST_CHECK_EQUAL(FormatParagraph("", 79, 0), "");
    BOOST_CHECK_EQUAL(FormatParagraph("test", 79, 0), "test");
    BOOST_CHECK_EQUAL(FormatParagraph(" test", 79, 0), " test");
    BOOST_CHECK_EQUAL(FormatParagraph("test test", 79, 0), "test test");
    BOOST_CHECK_EQUAL(FormatParagraph("test test", 4, 0), "test\ntest");
    BOOST_CHECK_EQUAL(FormatParagraph("testerde test", 4, 0), "testerde\ntest");
    BOOST_CHECK_EQUAL(FormatParagraph("test test", 4, 4), "test\n    test");
    
    BOOST_CHECK_EQUAL(FormatParagraph("test test\nabc", 4, 4), "test\n    test\nabc");
    BOOST_CHECK_EQUAL(FormatParagraph("This_is_a_very_long_test_string_without_any_spaces_so_it_should_just_get_returned_as_is_despite_the_length until it gets here", 79), "This_is_a_very_long_test_string_without_any_spaces_so_it_should_just_get_returned_as_is_despite_the_length\nuntil it gets here");
    
    BOOST_CHECK_EQUAL(FormatParagraph("a b c d e f g h i j k l m n o p q r s t u v w x y z 1 2 3 4 5 6 7 8 9 a b c de f g h i j k l m n o p", 79), "a b c d e f g h i j k l m n o p q r s t u v w x y z 1 2 3 4 5 6 7 8 9 a b c de\nf g h i j k l m n o p");
    BOOST_CHECK_EQUAL(FormatParagraph("x\na b c d e f g h i j k l m n o p q r s t u v w x y z 1 2 3 4 5 6 7 8 9 a b c de f g h i j k l m n o p", 79), "x\na b c d e f g h i j k l m n o p q r s t u v w x y z 1 2 3 4 5 6 7 8 9 a b c de\nf g h i j k l m n o p");
    
    BOOST_CHECK_EQUAL(FormatParagraph("x\na b c d e f g h i j k l m n o p q r s t u v w x y z 1 2 3 4 5 6 7 8 9 a b c de f g h i j k l m n o p q r s t u v w x y z 0 1 2 3 4 5 6 7 8 9 a b c d e fg h i j k", 79, 4), "x\na b c d e f g h i j k l m n o p q r s t u v w x y z 1 2 3 4 5 6 7 8 9 a b c de\n    f g h i j k l m n o p q r s t u v w x y z 0 1 2 3 4 5 6 7 8 9 a b c d e fg\n    h i j k");
    BOOST_CHECK_EQUAL(FormatParagraph("This is a very long test string. This is a second sentence in the very long test string.", 79), "This is a very long test string. This is a second sentence in the very long\ntest string.");
    BOOST_CHECK_EQUAL(FormatParagraph("This is a very long test string.\nThis is a second sentence in the very long test string. This is a third sentence in the very long test string.", 79), "This is a very long test string.\nThis is a second sentence in the very long test string. This is a third\nsentence in the very long test string.");
    BOOST_CHECK_EQUAL(FormatParagraph("This is a very long test string.\n\nThis is a second sentence in the very long test string. This is a third sentence in the very long test string.", 79), "This is a very long test string.\n\nThis is a second sentence in the very long test string. This is a third\nsentence in the very long test string.");
    BOOST_CHECK_EQUAL(FormatParagraph("Testing that normal newlines do not get indented.\nLike here.", 79), "Testing that normal newlines do not get indented.\nLike here.");
}
BOOST_AUTO_TEST_CASE(test_FormatSubVersion)