[FEATURE REQ] PolicyExemption ResourceSelector attributes are in GA, however API spec is still in Preview

### API Spec link

https://github.com/Azure/azure-rest-api-specs/blob/main/specification/resources/resource-manager/Microsoft.Authorization/preview/2024-12-01-preview/policyExemptions.json

### API Spec version

2024-12-01-preview

### Please describe the feature.

We would like to leverage the ResourceSelector attributes for making more specific Policy Exemptions in our organisation. We're a heavy user of Policy as Code in Ahold Delhaize through Terraform, however due to the fact that this API is still in preview we cannot implement the change in the Azure Terraform provider to expose these attributes.

@robga, can you look at this request? We got the recommendation to use AZApi instead, however that would require us to recreate all of our policy exemptions, of which we have a couple of thousand. This would be a huge risk, and would also cause some downtime while we recreate the policies due to some of them being Deny policies.

Start with specification/resources/resource-manager/Microsoft.Authorization/preview/2024-12-01-preview/policyExemptions.json and review how the ResourceSelector attributes are represented. Confirm the appropriate GA API version and the repository’s process for promoting this specification; done means the PolicyExemption ResourceSelector attributes are available in the supported GA API spec.

Written by the indexing model from the issue text.