Expose wait_for_steady_state and deployment_circuit_breaker (#55)

* Improve readability of container definition

This commit replaces the heredoc container definition and instead composes it from local variables to improve readability.

* Expose wait_for_steady_state for ECS service

This allows us to optionally wait for the ECS deployment to reach a steady state before terraform exits.

* Expose deployment_circuit_breaker configuration

The deployment circuit breaker allows services using the ECS deployment controller to fail a deployment (and optionally rollback) when the new tasks fail to stabilize.

* Update go dependencies for end to end tests

Terraform 0.14 changed the format of outputs, which causes the e2e tests to fail because terratest
is returning a quoted string with the cluster/service ARNs. The latest version contains a fix:
gruntwork-io/terratest@7829323

go.mod

@@ -3,15 +3,9 @@ module github.com/telia-oss/terraform-aws-ecs-fargate/v3
 go 1.12
 
 require (
-	github.com/aws/aws-sdk-go v1.23.12
-	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/gruntwork-io/terratest v0.18.5
-	github.com/kr/pretty v0.1.0 // indirect
-	github.com/magiconair/properties v1.8.1 // indirect
-	github.com/stretchr/testify v1.4.0
-	golang.org/x/crypto v0.0.0-20190829043050-9756ffdc2472 // indirect
-	golang.org/x/net v0.0.0-20190827160401-ba9fcec4b297 // indirect
-	golang.org/x/sys v0.0.0-20190830080133-08d80c9d36de // indirect
-	golang.org/x/text v0.3.2 // indirect
-	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect
+	github.com/aws/aws-sdk-go v1.38.64
+	github.com/gruntwork-io/terratest v0.36.0
+	github.com/stretchr/testify v1.7.0
+	gopkg.in/yaml.v2 v2.4.0 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )