Allow SimpleJobBuilder to start with JobExecutionDecider

[seonWKim]

Modification

• Add below method to allow users to specify JobExecutionDecider in the start(...) method as an argument.

JobBuilder.java

public JobFlowBuilder start(JobExecutionDecider decider) {
  return new SimpleJobBuilder(this).start(decider);
}

I found that we already have SimpleJobBuilder method that can start with JobExecutionDecider. So I think it's possible to add a method that utilizes SimpleJobBuilder's method(above mentioned) which will allow users to specify JobExecutionDecider as an argument of start method.

Resolves: #4411

[fmbenhassine]

Planning to include this in 5.1.0-M2. Can you please add the modifications as mentioned here: #4359 (comment) ? Currently, the method FlowJobBuilder#start(JobExecutionDecider) is missing in this PR.

Please update the tests of FlowJobBuilder as well and add the javadoc for new public methods. Thank you upfront.

[seonWKim]

@fmbenhassine Thank you for the detailed information. I've added missing method(FlowJobBuilder#start(JobExecutionDecider), javadoc and tests.

[fmbenhassine]

Great 👍 Thank you for the updates. Rebased and merged as 3fe3b7f.

Thank you for your contribution!