Do not open new documents if opened in new window

[philliphoff]

If the user opts to create a new Python (V2) project and open it in a new window, the extension currently attempts to open the new function_app.py and getting started Markdown files in the current window.

Unfortunately, the mechanism used to open the new project in a new window doesn't allow the extension to also specify an initial set of files to open. However, at the very least, the extension shouldn't open files in the current window.