Use ALIAS instead of CNAME with Route53?

**Issue/question**
Amplify sets up a CNAME pointing to a CloudFormation distribution in my hosted zone. I expected it to set up an ALIAS record.

**Additional information**
One of the selling points of Route53 is that it supports ALIAS records for AWS resources, and that you don't pay for DNS lookups for these. Is there any reason Amplify can't use ALIAS records instead of CNAME when creating records in Route53?

Start by locating the Route53 record-creation path and checking how the CloudFormation distribution target is represented. Done means determining whether an ALIAS can replace the CNAME without breaking custom-domain setup, then documenting or implementing the decision with coverage for the resulting record.

Written by the indexing model from the issue text.