Modernize build tooling and tuple string hashing support

[peter-lawrey]

Summary

This PR includes more than formatting cleanup. In addition to normalizing code style, imports, annotations, and Javadocs, it makes several substantive updates:

• Updates the GitHub Actions build workflow to current action versions and configures Temurin for JDK 11.
• Extends the compile-time sun.misc.Unsafe stub with additional methods needed by the codebase.
• Adds tuple-hash support to StringHash, allowing JVM-specific string hashing strategies to write directly into LongTupleHashFunction result arrays.
• Adds long-hash helper accessors for 128-bit Murmur3/XXH3 paths where the low 64-bit result is needed.
• Keeps the remaining formatting/readability changes mechanical, including import cleanup, spacing, cast formatting, and annotation/override adjustments.

[sonarqubecloud]

Quality Gate passed

Issues
5 New issues
0 Accepted issues

Measures
0 Security Hotspots
90.9% Coverage on New Code
1.7% Duplication on New Code

See analysis details on SonarQube Cloud

[sonarqubecloud]

❌ The last analysis has failed.

See analysis details on SonarQube Cloud