[python] add support for internal params and properties

[iscai-msft]

We added support for this in tcgc, but never in python (see tcgc pr here).

[msyyc]

There is no similar test case in spector https://github.com/Azure/typespec-azure/blob/main/packages/azure-http-specs/specs/azure/client-generator-core/access/main.tsp so we need add a case.