top-level-resources-list-by-subscription lint rule shouldn't be applied to extension resources

**Describe the bug**
This is in regards to lint rule [top-level-resources-list-by-subscription.md](https://github.com/Azure/azure-openapi-validator/blob/main/docs/top-level-resources-list-by-subscription.md). This rule shouldn't be applied to extension resources, with the Uri format /{resourceUri}/providers/{providerNamespace}/{resourceType}/{resourceName}.
Reference - https://github.com/Azure/azure-rest-api-specs-pr/pull/13667/checks?check_run_id=15314422918

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