[Java] Provide functionality to efficiently compute hash code for arbitrary memory segment

[asfimport]

This issue adds a functionality to efficiently compute  the hash code for a consecutive memory region. This functionality is important in practical scenarios because it helps:

• Avoid unnecessary memory copy.

• Avoid repeated conversions between Java objects & Arrow buffers. 

  Since the algorithm for calculating hash code has  significant performance implications, we need to design an interface so that different algorithms can be easily introduces as plug-ins.

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

PRs and other links:

• GitHub Pull Request #4844

_{Note: This issue was originally created as ARROW-5898. Please see the migration documentation for further details.}

[asfimport]

Micah Kornfield / @emkornfield:
Issue resolved by pull request 4844
#4844