[Bug]: missing-x-ms-identifiers rule produces false positives on 'extends' properties

[darkoa-msft]

Describe the bug

missing-x-ms-identifiers rule does not check base model for the existence of the identifier.

Reproduction

model UpdateFile extends UpdateFileBase {
  @OpenAPI.extension("x-ms-identifiers", [])
  relatedFiles?: UpdateFileBase[];
}

model UpdateFileBase {
  fileName: string;
}

@OpenAPI.extension("x-ms-identifiers", ["fileName"])
  files?: UpdateFile[];

@azure-tools/typespec-azure-resource-manager/missing-x-ms-identifiers: Property "fileName" is not found in "UpdateFile". Make sure value of x-ms-identifiers extension are valid property name of the array element.

Checklist

• Follow our Code of Conduct
• Check that this issue is about the Azure libraries for typespec. For bug in the typespec language or core libraries file it in the TypeSpec repo
• Check that there isn't already an issue that request the same bug to avoid creating a duplicate.
• The provided reproduction is a minimal reproducible example of the bug.