Add Java-generated Rust parity fixtures for regex crate upgrades

[sam-1112]

What is the problem the feature request solves?

The CometRegex whitelist introduced by PR #5415 depends on the semantics and compilation behavior of the locked Rust regex crate.

The existing CometRegexParitySuite exercises the native kernel, but its admitted pattern corpus is relatively small. A future regex crate upgrade could change the result or compilation status of an admitted pattern without the current corpus detecting it.

This creates coupling between the plan-time admission rules and the specific regex crate version.

Describe the potential solution

Generate a committed table of (pattern, subject, expected) fixtures using Java's Pattern.matcher(subject).find() and execute those fixtures directly in the Rust rlike unit tests.

The fixtures should cover:

• every construct currently admitted by CometRegex;
• concatenation and alternation combinations;
• capturing and non-capturing groups;
• character classes, ranges, negated classes, and escaped literals;
• greedy and counted quantifiers;
• empty-match cases;
• ASCII, non-ASCII, control-character, newline, and supplementary-code-point subjects;
• representative patterns near the conservative structural limits.

Document the JDK version and fixture-generation process. The committed Rust test should not require a JVM and should report the pattern, subject, expected result, and actual result on failure.

A Rust regex crate upgrade that changes the semantics or compilation status of an admitted fixture should cause this test to fail until the change is deliberately evaluated.

Additional context

Follow-up from #5415 and #5351.

This tracks the Rust-side Java-generated fixture table requested during review of #5415: #5415 (review)

The review specifically highlighted the regex crate-version coupling.

[mizulun]

take