feat(cloudfront): new aws-cloudfront-origins module, support for ALB/…

…NLB origins (#9209)

This change creates a new, dedicated aws-cloudfront-origins module to hold
convenience methods for constructing origins based on other constructs. The
initial set of supported origin types are S3 buckets, app and network load
balancers, and fallback support for any other HTTP server.

Future work in this space might include using properties of the constructs to
automatically configure the origins in optimal ways. For example, gaining access
to the load balancers' listeners to determine which port(s) CloudFront should
connect to.

Notes:
- It's worth someone challenging whether this is necessary. Most of the
  origin implementations are reasonably straightforward and could be
  included directly in the aws-cloudfront module.
- I wanted -- for non-S3 origins -- to expose the full set of configurable
  options, but didn't want to force users to specify the domain name, so split
  the *Origin Props into Options/Props, with the latter requiring the domain
  name. Open to other suggestions on how to achieve this (or arguments that the
  `S3Origin` should have this support as well).

fixes #9207


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*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/decdk/package.json

@@ -57,6 +57,7 @@
     "@aws-cdk/aws-cloud9": "0.0.0",
     "@aws-cdk/aws-cloudformation": "0.0.0",
     "@aws-cdk/aws-cloudfront": "0.0.0",
+    "@aws-cdk/aws-cloudfront-origins": "0.0.0",
     "@aws-cdk/aws-cloudtrail": "0.0.0",
     "@aws-cdk/aws-cloudwatch": "0.0.0",
     "@aws-cdk/aws-cloudwatch-actions": "0.0.0",