PLAT-709 Add Fargate Alarms

[oielbanna]

What changed?

• This PR uses cdk-monitoring-constructs to add the following alarms
  • WorkerErrors: measured errors in task execution based on log group metric filter
  • CpiUtilization of the service
  • MemoryUtilization of the service
  • QueueSize if it gets too large
  • DeadLetterQueueSize if any messages exist
• The monitoring object is exposed as a public readonly class member in case users want to add additional alarms
• The properties object alarms forces users to have an alarm on this system while giving them more alarm configuration options.

[jlouk]

Before you merge, can you take a look at the codebuild-helper?