[RocksJava] Filters getting disposed by System.gc before EOL

This commit solves two major problems with BloomFilters in RocksJava

The first problem which is solved by this commit is:
If the BloomFilter is passed as parameter it will be removed at the first GC cycle if BlockBasedTableConfig is not held anywhere. The solution to this is to keep references
to intermediate structures within the options.

The second problem is reference handling and ownership:
If the system sets multiple BloomFilters to the same BlockBasedTableConfig upon setting the second one the first reference is freed by the underlying c++ code. What leads to a Segfault on
freeing the BloomFilter Java instance.

Both problems are reproducable by just copying the test to the current master and executing the test.