smithy-aws-cloudformation-traits does not mark top-level properties as required

[workeitel]

The CloudFormation Resource type schema https://docs.aws.amazon.com/cloudformation-cli/latest/userguide/resource-type-schema.html allows to define properties required. Smithy currently does not mark top-level non-optional properties in the required section:

{
   ...
    "properties": {
         "propertyName": {
            "description": "string",
            "type": "string",
             . . . 
        },
 
        },
    },
    "required": [   // not added in Smithy
        "propertyName"
    ],
   ...

[kstich]

Looks like we'll need to add support for determining this field and the new conditionalCreateOnlyProperties field.

For now, you can set these properties directly with the jsonAdd configuration setting:

"jsonAdd": {
    "smithy.example#Queue": {
        "/required": [
            "propertyName"
        ]
    }
}