Specify the task CPU and memory (IT-4056)

[tschaffter]

Closes https://sagebionetworks.jira.com/browse/IT-4056

Changelog

• Add a class for specifying valid task CPU and memory pairs.
• Set container max memory to align with task max memory.

[tschaffter]

I realize that each task must share its resources with two more containers:

• ecs-service-connect: no CPU and memory limit visible in AWS Console.
• aws-guardduty-agent: hard max memory limit set to .125 GB.

One solution is to increment the memory made available to the task. The increment is usually 1 GB, which costs $3.20 / month (see Fargate pricing). So for 13 tasks, that about $40 / month / environment or a total of $1440 / year.

Alternatively, we could keep the memory allocated to the tasks as defined in this PR, but reduce the memory allocated to the OC container. Unlike the task definition, containers added to a task can have their memory set freely (no fixed increments) as long as the value is not larger that the memory allocated to the task.

memory_limit_mib (Union[int, float, None]) – The amount (in MiB) of memory to present to the container. If your container attempts to exceed the allocated memory, the container is terminated. At least one of memoryLimitMiB and memoryReservationMiB is required for non-Fargate services. Default: - No memory limit.