Add a construct to make/schedule AWS API calls

[jogold]

The cdk could benefit from an AwsLambda or ScheduledAwsLambda construct that could be used like this:

new ScheduledAwsLambda(this, 'StopInstance', {
  service: 'RDS',
  action: 'stopDBInstance',
  parameters: {
    DBInstanceIdentifier: '...',
  },
  scheduleExpression: 'cron(0 1 * * ? *)'
});

new ScheduledAwsLambda(this, 'StartExecution', {
  service: 'StepFunctions',
  action: 'startExecution',
  parameters: {
    stateMachineArn: '...',
  },
  scheduleExpression: 'cron(0 1 * * ? *)',
});

The lambda function takes the service, action and parameter as event and simply makes the call using aws-sdk-js.

See also discussion started in #1850

[jogold]

@eladb how about "generating" the code for these classes from the JSON files or type definitions of the aws-sdk?

So if I want to roll a container everyday at midnight I could do:

new ScheduledAwsEcsUpdateService(this, 'Roll', { // The class for the ECS.UpdateService API call
  params: { // This is typed :)
    service: myService.serviceName,
    cluster: myCluster.clusterName,
    forceNewDeployment: true
  },
  scheduleExpression: 'cron(0 0 * * ? *)'
});