feat(java): add fory json serialization

[chaokunyang]

Why?

Fory Java needs a first-class JSON serialization path that keeps Fory's field-based data model and TypeRef-aware type resolution while providing competitive parse and write throughput for String and UTF-8 inputs.

What does this PR do?

• Adds the standalone fory-json Java module and wires it into the Java build.
• Adds public JSON APIs including ForyJson, ForyJsonBuilder, JSONObject, JSONArray, ForyJsonException, and @JsonIgnore.
• Implements field-based codecs for objects, scalars, arrays, collections, and maps, including generic TypeRef root reads.
• Adds generated object codecs plus layout-specific readers and writers for Latin1 strings, UTF16 strings, and UTF-8 bytes.
• Adds JSON metadata, resolver, reader, writer, codegen, benchmark, and test coverage for the new module.
• Adds the small core codegen, memory, field-access, and string-layout hooks needed by the JSON module.

This is still in the early stage, more works will be submitted in follow-up prs.

Related issues

None.

Does this PR introduce any user-facing change?

• Does this PR introduce any public API change?
• Does this PR introduce any binary protocol compatibility change?

This adds the new Java fory-json module and public JSON APIs. It does not change the Fory binary or xlang wire protocol.

Benchmark

Latest JDK21 single-thread Eishay gate after optimization, compared against same-run registered Fory binary lanes:

• JSON parse String: 95.2% of registered Fory binary parse
• JSON parse UTF8: 93.7% of registered Fory binary parse
• JSON write String: 92.2% of registered Fory binary write
• JSON write UTF8: 90.7% of registered Fory binary write

JMH Perf result:

• EishayParseString.foryJson thrpt 3 6925519.766 ± 423432.614 ops/s
• EishayWriteString.foryJson thrpt 3 8974737.287 ± 681622.845 ops/s