Add Abnormal States Resolver interface and configuration item.

[jiajunwang]

Issues

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

#1027

Description

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

The Abnormal States Resolver defines a generic interface to find and recover if the partition has any abnormal current states. For example,

• double masters
• application data out of sync
  The interface shall be implemented according to the requirement.

The resolver is applied in the rebalance process according to the corresponding cluster config item. For example,
"ABNORMAL_STATES_RESOLVER_MAP" : {
"MASTERSLAVE" : "org.apache.helix.api.rebalancer.constraint.MasterSlaveAbnormalStateReslovler"
}
The default behavior without any configuration is not doing any recovery work.

Tests

• The following tests are written for this issue:

TestAbnormalStatesResolver
TestClusterConfig.testAbnormalStatesResolverConfig()

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

helix-rest, All passed

helix-core,
[ERROR] Failures:
[ERROR] TestRebalanceRunningTask.testFixedTargetTaskAndEnabledRebalanceAndNodeAdded:330 expected: but was:
[ERROR] TestTaskThrottling.testTaskThrottle:98 expected:<10> but was:<0>
[ERROR] TestWorkflowTimeout.testWorkflowTimeoutWhenWorkflowCompleted:116 expected: but was:
[INFO]
[ERROR] Tests run: 1148, Failures: 3, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------

Rerun
[INFO] Tests run: 10, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 50.296 s - in TestSuite
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 10, Failures: 0, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 56.539 s
[INFO] Finished at: 2020-05-27T09:53:49-07:00
[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

[jiajunwang]

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

[jiajunwang]

Will checkin to a separate branch for reviewing the later PRs.