[ECS] [Service Connect]: Allow option to register cloudmap record in route53

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**Tell us about your request**

Currently when Service Connect creates a service in Cloudmap it is set to be discoverable by API only. This makes it difficult when external services may need to connect to one of the services (lambdas are a good example).

**Which service(s) is this request for?**

ECS

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**

We want to connect from an external source to a service inside ECS Service Connect. Currently there is no simple way of doing this.

Without Service Connect in the picture, we can just connect to the record registered via Service Discovery which allows for both API and DNS discovery.

**Are you currently working around this issue?**

In addition to service connect configuration, an additional configuration can be passed to create an extra service discovery record.

So for example there is a service name `test` configured with service connect in the `example.local` namespace. everything inside the mesh/connect uses `test.example.local` to reach it.

Additionally we create a service discovery service names `test-external` and register it into the same namespace. External things like lambdas then connect on `test-external.example.local`

This works, but its clunky and should not be necessary.

**Additional context**

This more accurately describes the problem raised by https://github.com/aws/containers-roadmap/issues/2344