IngestExternalFileOptions update Java API to include several recently added option, in parity with C++

[alanpaxton]

The C++ API IngestExternalFileOptions has options that are not present in the Java API. We have added Java version of these C++ options:

verify_checksums_before_ingest verify_checksums_readahead_size verify_file_checksum fail_if_not_bottommost_level link_files

The Java options are named in camelCase per Java standards. The fail_if_not_bottommost_level has been named failIfNotLastLevel per the discussion in the code comments.