Adds propagate_tags to ecs service, task role output

[alexmaras]

I've got two changes bundled up here:

1. add propagate_tags to all aws_ecs_service resources, and a variable task_propagate_tags to control it. This allows for accurate cost tracking in AWS, as previously, the ECS tasks weren't tagged at all when run. This accounts for a large portion of the cost.
2. add the IAM task role name and ARN as outputs. This allows for permissions to be added to tasks, such as accessing secrets manager, without directly editing the module.

becomes