[Feature Request] Add a Service filter under swagger resource provider filter

In [Azure Service Versioning guideline](https://github.com/Azure/azure-rest-api-specs/wiki/Azure-Service-Versioning-Guideline), we have been decoupling the concept of a Service 1:1 mapping with a RP namespace so that service team have the ability to extend to multiple service pattern without having to apply independent RP namespace or service tree nodes.

In order to do that, we have a new [spec folder structure guideline](https://github.com/Azure/azure-rest-api-specs/wiki/Specification-Folder-Structure-Guide) and most of the ARM services have been migrated to the new folder structure guideline, and some of them has already adopted to the multiple services patterns like monitoring services https://github.com/Azure/azure-rest-api-specs/tree/main/specification/monitoringservice/resource-manager/Microsoft.Monitor which has three different independent services Accounts, PipelineGroups, Slis and each of them can have independent SDKs/CLIs/Docs. Similar like [Compute](https://github.com/Azure/azure-rest-api-specs/tree/main/specification/compute/resource-manager/Microsoft.Compute), [ContainerService](https://github.com/Azure/azure-rest-api-specs/tree/main/specification/containerservice/resource-manager/Microsoft.ContainerService)

Currently the aaz-dev tool, only allows customer to filter the APIs from resource provider layer, which would add additional costs for service team who are in a multiple service pattern to filter their own APIs. Which is not convenient and might cause unnecessary human mistakes when choosing APIs among many of them.

Therefore, I would like to ask for a **Service filter** under the resource provider feature request so that service team can locate their own service API specs more easily.