feat: CloudFormation docs in schema

[hoffa]

Issue #, if available

Description of changes

Full diff here: https://github.com/aws/serverless-application-model/pull/2816.diff

Adds CloudFormation docs to schema:

Currently uses heuristics to guess the documentation page matching definitions in the CloudFormation JSON schema.

It works reasonably well (e.g. AWS::EC2::CapacityReservationFleet.TagSpecification corresponds to aws-properties-ec2-capacityreservation-tagspecification.md), but there are exceptions such as AWS::EC2::Instance.Ebs which correspond to aws-properties-ec2-blockdev-template.md. 🤔

There are probably more robust ways of cross-referencing, without depending on a specific format as provided by GoFormation, and without heuristics (e.g. using the CloudFormation resource specification, which includes a Documentation URL which has the correct slug).

The decompressed sizes are relatively large (7 to 11 MB), but all compress nicely (3 MB in total gzipped).

Description of how you validated changes

Checked diff and tested sample templates in VS Code.

Checklist

• Adheres to the development guidelines
• Add/update transform tests
  • Using correct values
  • Using wrong values
• Add/update integration tests

Examples?

Please reach out in the comments if you want to add an example. Examples will be
added to sam init through aws/aws-sam-cli-app-templates.

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