[Java] Provide parallel searcher

[asfimport]

For scenarios where the vector is large and the a low response time is required, we need to search the vector in parallel to improve the responsiveness.

This issue tries to provide a parallel searcher for the equality semantics (the support for ordering semantics is not ready yet, as we need a way to distribute the comparator).

The implementation is based on multi-threading.

Reporter: Liya Fan / @liyafan82
Assignee: Liya Fan / @liyafan82

PRs and other links:

• GitHub Pull Request #5631

_{Note: This issue was originally created as ARROW-6863. Please see the migration documentation for further details.}

[asfimport]

Neal Richardson / @nealrichardson:
Issue resolved by pull request 5631
#5631