* provider/aws: CodeDeploy Deployment Group Triggers
- Create a Trigger to Send Notifications for AWS CodeDeploy Events
- Update aws_codedeploy_deployment_group docs
* Refactor validateTriggerEvent function and test
- also rename TestAccAWSCodeDeployDeploymentGroup_triggerConfiguration test
* Enhance existing Deployment Group integration tests
- by using built in resource attribute helpers
- these can get quite verbose and repetitive, so passing the resource to a function might be better
- can't use these (yet) to assert trigger configuration state
* Unit tests for conversions between aws TriggerConfig and terraform resource schema
- buildTriggerConfigs
- triggerConfigsToMap
