Add java-util to Utility section

[jdereg]

java-util is a zero-dependency collection of high-performance Java utilities that has been available on Maven Central since 2014.

What distinguishes it from other entries in Utility:

• Zero runtime dependencies — the single ~700K JAR works from JDK 8 through JDK 24
• Converter — universal type conversion across 750+ type pairs with a single convert(source, TargetType.class) API, filling a gap the JDK has never addressed
• DeepEquals — recursive object graph comparison handling cycles, collections, maps, and arrays — something Arrays.deepEquals() cannot do for arbitrary objects
• CaseInsensitiveMap — O(1) case-insensitive key lookup (the JDK TreeMap workaround is O(log n)), with thread-safe variants
• TTLCache — lightweight, thread-safe caching with time-based expiration and optional LRU eviction, without pulling in a full caching framework
• CompactMap — self-optimizing storage that switches internal representation based on size, reducing memory for millions of small maps
• MultiKeyMap — N-dimensional composite-key mapping with typed array support for complex lookup scenarios
• Object graph traversal — Traverser for walking arbitrary object graphs with visitor pattern and cycle detection

It is Apache 2.0 licensed, actively maintained, and has been used in production for over 10 years.