AWS Batch Job attempts implemented

[ChristianKniep]

I'd like to use the AWS Batch internal Job attempts configuration within a job. So far I was only able to have miniWDL create a new job if a job fails.
Any chance that I just overlooked the right place to enable jobAttempts?

[mlin]

@ChristianKniep Unfortunately miniwdl needs to use its own retry logic instead of Batch's because it does some stateful stuff on the filesystem in the setup & teardown of each attempt, so they would not be idempotent if controlled by Batch. The miniwdl retry logic is controlled by the runtime.maxRetries and runtime.preemptible attributes on each task.