`Mobile Network`: `PacketCoreControlPlane` lacks `baseVM` definition of `platformType`

for the [`PlatformType`](https://github.com/Azure/azure-rest-api-specs/blob/main/specification/mobilenetwork/resource-manager/Microsoft.MobileNetwork/stable/2022-11-01/packetCoreControlPlane.json#L771), the `BaseVM` has been removed from ENUM, but it actually being used, so please add it back to Swagger. If it's going to be deprecated, please limit it on service side instead of just removing it from Swagger.

Start with specification/mobilenetwork/resource-manager/Microsoft.MobileNetwork/stable/2022-11-01/packetCoreControlPlane.json and inspect the PlatformType definition around line 771. Confirm how BaseVM is used, then restore it to the enum if appropriate. Done means the Swagger definition represents the service's accepted PlatformType values, including BaseVM.

Written by the indexing model from the issue text.