Reject Tor versions that contain non-numeric prefixes

In #21450 (moved), we made tor_version_parse use:

tor_parse_uint64(... , 10, 0, INT32_MAX, ...);

But this still allows versions that start with: an arbitrary amount of white space (as determined by isspace(3)) followed by a single optional "+" or "-" sign

This doesn't fit the version spec, and we should fix it. This is an issue that's existed since we started parsing tor versions.