Add a simple Zk Distributed Lock

[narendly]

Issues

• My PR addresses the following Helix issues and references them in the PR description:

#672

Description

• Here are some details about my PR, including screenshots of any UI changes:

This distributed lock implementation could be included in the distributed lock module. This is a canonical implementation of ZK-based distributed lock. Note that this is a blocking lock.

Tests

• The following tests are written for this issue:

Manually tested.
TODO

• The following is the result of the "mvn test" command on the appropriate module:

TODO

Commits

• My commits all reference appropriate Apache Helix GitHub issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters (not including Jira issue reference)
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

Code Quality

• My diff has been formatted using helix-style.xml

[jiajunwang]

@narendly if this PR is not intended to be merged now, could you please close it?

[jiajunwang]

Close due to inactive.