Added optional CI_AWS_ECS_CONTAINER_NAME variable to ECS
Added optional CI_AWS_ECS_CONTAINER_NAME variable to ECS to allow specifying which container definition to update. Previously, the default action was to update the image tag of the first container definition in the list of container definitions in the task definition. Now, if the CI_AWS_ECS_CONTAINER_NAME variable is set, only the container definition that matches the specified name will have its image updated.
This is in line with AWS' own aws-actions/amazon-ecs-render-task-definition@v1 GitHub Action, which allows you to specify which "container-image" you want to update.