Add CloudConfig operations

[alirezazamani]

Issues

• My PR addresses the following Helix issues and references them in the PR title:
  Fixes TODO: Add CloudConfig to support cluster creation in cloud environments #588 .

Description

• Here are some details about my PR, including screenshots of any UI changes:
  In order to move toward supporting cloud environments, we need to add CloudConfig to Zookeeper. The CloudConfig information will be used by the participants for autojoining.
  In this commit:
  The code regarding CloudConfig is added. A new test has been added to check the correctness of the code.

Tests

• The following is the result of the "mvn test" command on the appropriate module:
  A new test has been added. (TestCloudConfig)

Test Result 1: mvn test
[ERROR] Tests run: 883, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 3,234.951 s <<< FAILURE! - in TestSuite
[ERROR] testTaskPerformanceMetrics(org.apache.helix.monitoring.mbeans.TestTaskPerformanceMetrics) Time elapsed: 2.22 s <<< FAILURE!
java.lang.AssertionError: expected: but was:
at org.apache.helix.monitoring.mbeans.TestTaskPerformanceMetrics.testTaskPerformanceMetrics(TestTaskPerformanceMetrics.java:118)

[INFO]
[INFO] Results:
[INFO]
[ERROR] Failures:
[ERROR] TestTaskPerformanceMetrics.testTaskPerformanceMetrics:118 expected: but was:
[INFO]
[ERROR] Tests run: 883, Failures: 1, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 53:59 min
[INFO] Finished at: 2019-11-12T15:32:39-08:00
[INFO] ------------------------------------------------------------------------

Test Result 2: mvn test -Dtest="TestTaskPerformanceMetrics"
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 16.397 s - in org.apache.helix.monitoring.mbeans.TestTaskPerformanceMetrics
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 21.497 s
[INFO] Finished at: 2019-11-12T15:46:06-08:00
[INFO] ------------------------------------------------------------------------

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

[alirezazamani]

@dasahcc When you get a chance, could you please review this PR based on our discussions?

[junkaixue]

Overall, LGTM. Let's wait for module and naming finalized before checked.

[junkaixue]

Overall, LGTM.

[alirezazamani]

This PR is ready to be merged, approved by @dasahcc.

Title: Add CloudConfig Related Code

Body:
In order to move toward supporting cloud environments and auto-registration,
we need to have a CloudConfig Znode under the Config.
In this commit, the code regarding the CloudConfig is added.