feat: implement Data::UUID in Java using java.util.UUID

[fglock]

Summary

Adds a Java XS implementation for the CPAN Data::UUID module under org.perlonjava.runtime.perlmodule.DataUUID, backed by java.util.UUID and java.security.MessageDigest (MD5).

Before this change, ./jcpan -t Data::UUID would install the .pm file but every test failed at use Data::UUID; with "Can't load loadable object for module Data::UUID: no Java XS implementation available" (Data::UUID ships no pure-Perl fallback).

After this change, the full CPAN test suite passes:

t/basic.t ................. ok
t/from-name-collisions.t .. ok
t/leaky_dollar_bang.t ..... ok
t/segv.t .................. ok
Files=7, Tests=32, Result: PASS

Implementation notes

• create() uses UUID.randomUUID() (v4). The CPAN XS implementation produces v1 time-based UUIDs, but no test relies on the specific version — they only require uniqueness and round-tripping, both of which v4 satisfies.
• create_from_name() implements RFC 4122 §4.3 directly: MD5(namespace_bytes || name_bytes), then sets version=3 and the RFC 4122 variant bits.
• NameSpace_{DNS,URL,OID,X500} registered as constant methods returning 16-byte binary namespace UUIDs. The CPAN UUID.pm's @EXPORT handles importing them at the call site.
• Binary representation: 16-byte big-endian (RFC 4122 canonical). Self-consistent with the to_/from_ conversions. Differs from the CPAN XS module's host-byte-order binary on little-endian platforms, but that format isn't portable across platforms either.
• checkSelf() enforces that instance methods are called on a blessed Data::UUID reference, matching the XS typemap behaviour that t/segv.t exercises (Data::UUID->create must die with "self is not of type Data::UUID").

Test plan

• jcpan -t Data::UUID → all tests pass (32/32)
• make → all unit tests pass, no regressions
• Manual round-trip smoke test: create → to_string → from_string → compare == 0
• Data::UUID->create (class method) dies with expected message

Related design doc: dev/modules/xs_fallback.md.

Generated with Devin