Support publishing additional artifacts

[aaronwalker]

I would be useful to be able to include additional artifacts in the S3 publish for components.

Use Case: The api gateway component supports loading a api swagger file from S3 so it would be useful to just include the api swagger definition is the published templates instead of requiring an additional deployment step

maybe something like

PublishArtifact file: "my-swagger.yaml", key: "my-swagger-#{component_version}.yaml"

or

S3Artifact file: "my-swagger.yaml", key: "my-swagger-#{component_version}.yaml"

The key could be optional

[aaronwalker]

@Guslington @toshke thoughts?

[Guslington]

@aaronwalker would it be worth exposing the artifact key value to a component

Api:
    Type: AWS::ApiGateway::RestApi
    Properties: 
    BodyS3Location: 
        Bucket: distribution_bucket
        Key: artifact_key['name']