Per SemVer 2.0.0 the core version numbers and numeric prerelease
identifiers must not include leading zeroes, and prerelease/build-metadata
identifiers must be composed only of ASCII alphanumerics and hyphens.
Add IsValidIdentifiers using a vectorized SearchValues lookup for the
allowed character set and ulong.TryParse to detect numeric identifiers
for the leading-zero check. Add failing-then-passing tests for both
invalid and still-valid inputs.
