Expose IngestExternalFileOptions::fill_cache in RocksJava

[richinmrudul]

Hi RocksDB maintainers,

C++ IngestExternalFileOptions exposes fill_cache, which controls whether data and metadata blocks read during file ingestion are added to the block cache.

This is useful for bulk-loading into a column family that is not available for reads yet, where users may want to avoid polluting the block cache during ingestion.

However, RocksJava's org.rocksdb.IngestExternalFileOptions does not currently expose this option.

Expected behavior:
RocksJava should expose getter/setter methods, likely:

boolean fillCache()
IngestExternalFileOptions setFillCache(boolean fillCache)