Expand the `AdditionalSchemaElement` properties allowed values

### Name of the resource

Other

### Resource name

AWS::Cur::ReportDefinition

### Description

Reviewing the resource schema, I noticed that the `AdditionalSchemaElement` has `Resources` as the only allowed value. Please see the schema below:

```
"AdditionalSchemaElements" : {
"description" : "A list of strings that indicate additional content that Amazon Web Services includes in the report, such as individual resource IDs.",
"type" : "array",
"default" : [ ],
"items" : {
"description" : "Whether or not AWS includes resource IDs in the report.",
"type" : "string",
"enum" : [ "RESOURCES" ]
}
}
```

This is inconsistent with the Valid Values in the AWS Billing and Cost Management API Reference. [[1]](https://docs.aws.amazon.com/aws-cost-management/latest/APIReference/API_cur_ReportDefinition.html#:~:text=AdditionalSchemaElements)

I would like for the `AdditionalSchemaElement` property to include the `SPLIT_COST_ALLOCATION_DATA` value. This is so that the allowed values in the Schema match the Valid Values.

### Other Details

_No response_

Locate the schema for AWS::Cur::ReportDefinition and inspect the AdditionalSchemaElements property, then compare its enum with the linked AWS Billing and Cost Management API reference. Done means the allowed values include both RESOURCES and SPLIT_COST_ALLOCATION_DATA.

Written by the indexing model from the issue text.