close #5920

Modifying canSubmit to avoid to avoid exceed executor.queueSize parameter.
Printing warning when array size exceeds the queueSize. This can make the task array 'unsubmitable' (Not sure if we should abort the execution in this situation)
Add unit tests
Tested with this pipeline

process test {
    array 10 
    input:
    val x

    """
    echo $x
    """
}

workflow {
   Channel.of(1..20) | test
}

With a config with awsbatch executor and different executor.queueSize values:

size 15: Only one job submitted at a time in AWS Batch.
size 5: Prints a warning but run continues without the task array jobs submitted.