Auto generate rules from AWS API models

[wata727]

This idea is to automatically generate basic validations from AWS API models, just like aws-sdk-go. We only manage mappings of Terraform resource attribute to AWS model shape name, and the rules are generated from the mappings automatically.

The following is an example of the mapping:

import = "aws-sdk-go/models/apis/ec2/2016-11-15/api-2.json"

mapping "aws_launch_template" {
  name = LaunchTemplateName
}

The API version is always assumed to be the latest version. It should be configurable for more accurate verification, but we will address it later.