Make ClusterSetup realm-aware

[narendly]

Issues

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

#860

Description

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

We make ClusterSetup, a Helix Java API, realm-aware so that this could be used in a multi-ZK environment.
Changelist:

1. Add a Builder to enable users to set internal ZkClient parameters
2. Add the realm-aware behavior in existing constructors

Tests

• The following tests are written for this issue:

TestClusterSetup covers this.

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

helix-core:

[INFO] Results:
[INFO] 
[ERROR] Failures: 
[ERROR]   TestHierarchicalDataStore.testHierarchicalDataStore:50->add:81 » ZkClient Inpu...
[ERROR]   TestEnableCompression.testEnableCompressionResource:108 expected:<true> but was:<false>
[ERROR]   TestControllerLeadershipChange.testMissingTopStateDurationMonitoring:262 expected:<true> but was:<false>
[INFO] 
[ERROR] Tests run: 1083, Failures: 3, Errors: 0, Skipped: 0
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  01:07 h
[INFO] Finished at: 2020-03-11T02:14:14-07:00
[INFO] ------------------------------------------------------------------------

All tests pass when run individually.

mvn test -Dtest=TestHierarchicalDataStore,TestEnableCompression,TestControllerLeadershipChange,TestConfigAccessor,TestClusterSetup

[INFO] Tests run: 19, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 76.508 s - in TestSuite
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 19, Failures: 0, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 02:37 min
[INFO] Finished at: 2020-03-11T19:34:16-07:00
[INFO] ------------------------------------------------------------------------

Commits

• My commits all reference appropriate Apache Helix GitHub issues in their subject lines. 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"

Documentation (Optional)

• In case of new functionality, my PR adds documentation in the following wiki page:

(Link the GitHub wiki you added)

Code Quality

• My diff has been formatted using helix-style.xml
  (helix-style-intellij.xml if IntelliJ IDE is used)

[junkaixue]

LGTM. But please address remaining concerns.

[narendly]

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

We make ClusterSetup, a Helix Java API, realm-aware so that this could be used in a multi-ZK environment.
Changelist:

Add a Builder to enable users to set internal ZkClient parameters
Add the realm-aware behavior in existing constructors