Add SecondaryCache support to Java API

[mike-evolved]

Changes:

• Add SecondaryCache abstract class with CompressedSecondaryCache implementation
• Add JNI bindings for CompressedSecondaryCacheOptions
• Extend LRUCache constructor to accept optional SecondaryCache
• Add comprehensive test suite (5 tests covering creation, integration, and large datasets)
• Update build configs (src.mk, java/Makefile, java/CMakeLists.txt)

Usage example:

try (SecondaryCache secondaryCache = SecondaryCache.newCompressedSecondaryCache(256 * 1024 * 1024);
     LRUCache primaryCache = new LRUCache(64 * 1024 * 1024, -1, false, 0.5, 0.0, secondaryCache)) {
  // Use cache with automatic promotion/demotion between tiers
}