Adopt the proposed Port Attributes API for python testing

[eleanorjboyd]

Python testing requires two ports the extension creates to communicate with the subprocess we spin up to run python tests. These are not ports that the user will need to access but instead internal so it applies to the same information as here: #21292

should help with #21929

@alexr00 tagging you as an FYI

[alexr00]

Let me know if you have any feedback on the Port Attributes API! The python debugger is also working on adopting this: microsoft/vscode-python-debugger#85

[eleanorjboyd]

since we are going to move to named pipes this is no longer applicable on our roadmap. Thanks!