Do Python debugging through the new Python Debug extension

[bwateratmsft]

According to https://code.visualstudio.com/updates/v1_86#_python-debugger-extension-installed-by-default, the Python extension is going to eventually drop debugging support, with support moved to a new Python Debugger extension. We need to react to this.

[bwateratmsft]

Blocked by microsoft/vscode-python-debugger#194

[bwateratmsft]

microsoft/vscode-python#23278

[bwateratmsft]

Reopening and removing from the milestone so we can retriage and decide if we want to do a servicing release for this.

[bwateratmsft]

Reclosing since we'll ship a 1.29.1 out of main