Add java API to create cluster with CloudConfig

[alirezazamani]

Issues

• My PR addresses the following Helix issues and references them in the PR title:
  Fixes TODO: Add relevant java Level APIs for cloudConfig creation #646.

Description

• Here are some details about my PR, including screenshots of any UI changes:
  In this commit the below APIs have been added.
  1- AddCluster with CloudCOnfig API.
  2- addCloudConfig to existing cluster.
  3- Update CloudConfig to update existing Cloud Config

Several tests have been added to validate these APIs.

Tests

• The following is the result of the "mvn test" command on the appropriate module:
  New tests have been added.
  TestConfigAccessor.testUpdateCloudConfig
  TestZkHelixAdmin.testAddCloudConfig
  TestClusterSetup.testAddClusterWithInvalidCloudConfig
  TestClusterSetup.testAddClusterWithValidCloudConfig
  TestClusterSetup.testAddClusterAzureProvider

Test Result 1: mvn test
[INFO] Tests run: 900, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 3,228.171 s - in TestSuite
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 900, Failures: 0, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 53:52 min
[INFO] Finished at: 2019-12-09T13:52:08-08:00
[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

[junkaixue]

Leave some minor comments. Overall, LGTM. Make sure you resolve other review comments.

[alirezazamani]

This PR is ready to be merged, approved by @zhangmeng916 and @dasahcc.

Final Commit message:
Title:
Add java API to create cluster with CloudConfig

Body:
In this commit the below APIs have been added.
1- AddCluster with CloudCOnfig API.
2- addCloudConfig to existing cluster.
3- Update CloudConfig to update existing Cloud Config.
Several tests have been added to test these APIs.