OAK-9790 - Implement parallel indexing for speeding up oak run indexing command

[Ewocker]

OAK-9790 - Implement parallel indexing for speeding up oak run indexing command

Since indexing was single threads, which is slow for large repository. In order to improve the indexing performance we need to implement parallel indexing.

The work is cover for both lucene and elastic indexing. In order to support parallel indexing, it need to split the big flat file store file ahead, which add a big overhead, but make parallel index possible and much faster.

Another change together is support the LZ4 compression since which is much faster compare to gzip.

[amit-jain]

New PR which incorporates the review comments https://github.com/apache/jackrabbit-oak/pull/715

[amit-jain]

superseded by PR https://github.com/apache/jackrabbit-oak/pull/715