Easier configuration of pythonpath

[mrgrieves4]

As a PyCharm user looking at vscode, one thing that I find pretty unintuitive and awkward is how the pythonpath is setup in vscode. IE having to create a magic file called .env and place a single PYTHONPATH listing all the folders, and there could be a lot of them.

In PyCharm I just need to right click folders and mark/unmark as sources root, and I can also view a list and edit them from there. (Similarly I can exclude folders like this too)

Preferably the config file should use relative paths and be sharable in a team.

Ideally if I rename a folder it would also update the config.

The other thing I found a little confusing is that "pythonpath" in settings etc seems to refer to an interpreter path rather than the actual pythonpath env var, which is what I was expecting it to mean.

[brettcannon]

We are dropping the python.pythonPath setting for python.defaultInterpreterPath, so that confusion will be taken care of shortly.

[brettcannon]

Moved to #17179