Add missing ListTagsForResource API

[Limess]

Would it be possible to cut a new release with the latest AWS API models to support this new API?

Version of AWS SDK for Go?

• aws-sdk-go-v2 v0.7.0
• master 80eda21e3854386d2a56de1236efe984f6e687de

Version of Go (go version)?

N/A

What issue did you see?

The Cloudwatch API ListTagsForResource is missing.

This does exist in the current V1 SDK (https://docs.aws.amazon.com/sdk-for-go/api/service/cloudwatch/#CloudWatch.ListTagsForResource)

[jasdel]

Thanks for reporting this issue @Limess. This is one of the API's the V2 SDK is lagging behind the V1 SDK's API models. Tagging this as a v1-sync so we can update the V2 SDK's API model definitions.