Explore how to notify the user they don't have Python installed when installing the Python extension for the first time

[brettcannon]

Could have the walkthrough hide all other steps and be very clear that Python could not be found.

Should probably stop having the error notification for this.

Could wire into all the places we need Python to do something (e.g. debugging, running, etc.) and have a modal dialog telling the user to please install Python.

[luabud]

Once we're done with the changes, we should update our docs to reflect that (#19168)

[karrtikr]

Options on how it indicate that through the walkthrough:

1. Display it as a separate title and hide it once we detect no Python is installed.
   Although this would mean there's a flicker when the tile disappears.
   

2. Merge it with "Select Interpreter" tile?
   That would make each step too verbose as that's a lot of a text in a single tile, also the body text could still change while the tile is opened.

3. Show it when Python: Select Interpreter is used to open quickpick.
   

In option 3. we need to render the markdown file similar to how getting started tile is rendered. Is it possible with markdown-it? Ideally it would be great we can simply bring Install tile to focus rather than opening a new tab.

Discussed with Luciana and decided not to go with option 3, working on a prototype for option 1 and 2 to see how it looks.

Could wire into all the places we need Python to do something (e.g. debugging, running, etc.) and have a modal dialog telling the user to please install Python.

Still planning on this.

[karrtikr]

Now that "Create Python file" is the first step, it's leading to some issues. The command for "Create Python file" is implemented by the extension which means until the extension is activated, the command does not work properly:

We could instead use VSCode's command to open an untitled file and direct users using that instead:

Ideally it would be great if VSCode itself can provide a command for creating a Python file directly.

[karrtikr]

Opened microsoft/vscode#152920 to support #19099 (comment). Created #19380 to track it.

[karrtikr]

• Remove Python is not installed prompt in favor of No Interpreter Selected prompt: Improve "No Python interpreter" selected prompt #17667. This will ensure when users finish installing Python from windows store, it shows up without reload when following the prompt to open the interpreter list.