When compiling without external signer support, the resulted `bench_bitcoin.exe` fails on Windows:
```
>.\bench_bitcoin.exe -filter=AddrManSelectByNetwork
Error: bad optional access
```

Steps to reproduce the failure:
- cross compiling on Ubuntu 22.04:
```
$ make -j $(nproc) -C depends HOST=x86_64-w64-mingw32 NO_QT=1
$ ./autogen.sh
$ ./configure CONFIG_SITE=$PWD/depends/x86_64-w64-mingw32/share/config.site --disable-external-signer
$ make -j $(nproc)
```
- compiling natively on Windows:

Apply the diff as follows:
```diff
--- a/build_msvc/bitcoin_config.h.in
+++ b/build_msvc/bitcoin_config.h.in
@@ -41,9 +41,6 @@
 /* Define this symbol to enable ZMQ functions */
 #define ENABLE_ZMQ 1
 
-/* define if external signer support is enabled (requires Boost::Process) */
-#define ENABLE_EXTERNAL_SIGNER /**/
-
 /* Define to 1 if you have the declaration of `be16toh', and to 0 if you
    don't. */
 #define HAVE_DECL_BE16TOH 0
```
Then
```
>py -3 build_msvc\msvc-autogen.py
>msbuild build_msvc\bitcoin.sln -property:Configuration=Release -verbosity:minimal
>src\bench_bitcoin.exe -filter=AddrManSelectByNetwork
Error: bad optional access
```

---

The failure does not manifest itself when running `bench_bitcoin.exe` using Wine on Linux.
result = TryParseHex<uint8_t>(" 89 34 56 78").value();
    BOOST_CHECK(result.size() == 4 && result[0] == 0x89 && result[1] == 0x34 && result[2] == 0x56 && result[3] == 0x78);
    
    result = ParseHex("     Ff        aA    ");
    BOOST_CHECK(result.size() == 2 && result[0] == 0xff && result[1] == 0xaa);
    result = TryParseHex<uint8_t>("     Ff        aA    ").value();
    BOOST_CHECK(result.size() == 2 && result[0] == 0xff && result[1] == 0xaa);
    
    result = ParseHex("");
    BOOST_CHECK(result.size() == 0);
    result = TryParseHex<uint8_t>("").value();
    BOOST_CHECK(result.size() == 0);
    
    BOOST_CHECK_EQUAL(ParseHex("AAF F").size(), 0);
    BOOST_CHECK(!TryParseHex("AAF F").has_value());
    
    const std::string with_embedded_null{" 11 "s
                                         " \0 "
                                         " 22 "s};
    BOOST_CHECK_EQUAL(with_embedded_null.size(), 11);
    BOOST_CHECK_EQUAL(ParseHex(with_embedded_null).size(), 0);
    BOOST_CHECK(!TryParseHex(with_embedded_null).has_value());
    
    BOOST_CHECK_EQUAL(ParseHex("1234 invalid 1234").size(), 0);
    BOOST_CHECK(!TryParseHex("1234 invalid 1234").has_value());
    
    BOOST_CHECK_EQUAL(ParseHex("12 3").size(), 0);
    BOOST_CHECK(!TryParseHex("12 3").has_value());
}
BOOST_AUTO_TEST_CASE(util_HexStr)