AWS Batch - add support for custom log group name and additional tags

[nathanthorpe]

Add the logGroupName and additionalTags config option to the default-runtime-attributes section of the AWS Batch configuration.

This enables you to send the logs to a custom log group name and tag the jobs that Cromwell submits.

Sample usage:

default-runtime-attributes {
    queueArn: "arn:aws:batch:us-east-1:111222333444:job-queue/job-queue"
    logGroupName: "/Cromwell/job/"
    additionalTags {
       projectid: "project1"
    }
}