chore(spec2cdk): generate ICfnResource interface

[kaizencc]

Generates something that looks like this for all resources:

interface ICfnResource {
  readonly attrName: string;    // { Ref }, i.e. the primaryIdentifier
  readonly attrArn: string;     // { Fn::GetAtt }, if applicable
}

In a separate PR, we will update all CfnResources to extend ICfnResource, and then later on, update some Resources to extend ICfnResource as well.

This PR targets conroy/generate as a horribly named branch off of main which will house all pieces of this puzzle before unleashing onto main.

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