Implement interactive window with VS code notebook API

[rchiodo]

TODO

• Support error link clicking in interactive window #6465
• Interactive Window - No sys info at the top when kernel doesn't launch #6462
• Interactive window on reload will not associate with the same python file #6421
• Interactive Window - switching kernels doesn't put up the switch kernel message until run a cell #6424
• Seeing squiggles in input editor #6449
• Restart kernel should be a modal dialog #6456
• Not seeing any suggestions in input editor #6458
• jupyter.alwaysScrollOnNewCell doesn't work on user input loop #4257
• Nothing happens when I click on collapse all #6457
• Interactive window makes cell markers disappear when a cell doesn't run #6418

This epic is switching the interactive window to use the VS code notebook API instead of our custom webview.

Here's a brief list of the requirements (in mostly priority order):

1. Support input from an external source (like a python file)` (already supported)
2. Show all cell outputs in a big read only list (already supported)
3. Support direct input from a text editor that doesn't move. (vscode upstream)
4. Support hiding/collapsing code in cells (vscode upstream - possibly part of Jupyter Outline) -- supported with notebook.cell.collapseCellInput command
5. Support copying code out of cells with some gesture (extension)
6. Support a history of text entered in the pinned text editor (extension)
7. Support theming (already supported)
8. Support intellisense (extension)
9. Support all cell outputs that a notebook does (already supported)
10. Support restarting/interrrupting kernel
11. Support variables
12. Scroll as new inputs come in (behave like chat window) (vscode upstream) -- supported with notebook focus commands:

[jlperla]

Out of curiosity, does the disaperring "interactive window" mean that you will no longer be able to use normal .py files and see the interactive results/plots as you can now? That is, will all interactive features will only be available in .ipynb files?

[rchiodo]

It's not disappearing. This issue is about reimplementing it with a different API.

[jlperla]

Thanks! Will it still be in a separate interactive window, or will it all be inline (Rmd style)?

[rchiodo]

Same way it works now. The chrome around cells and the toolbar might be different, but it will have the same basic functionality. That's what the list of requirements at the top are for - to make sure we don't regress anything that already works.

[jlperla]

Thank you so much, it is great to hear. Last question: any chance that the move to the new APIs will make the interactive window a little easier to open up (or at least fork) for other jupyter kernels, or is the plan still to be extremely tied to python for the medium-term?

[rchiodo]

Actually using other kernels will happen long before this work is done. In fact we already submitted preliminary support for it. Our next version should allow you to switch to other kernels. See this item:
microsoft/vscode-python#12096

[rchiodo]

I talk more about the limitations here:
https://github.com/microsoft/vscode-python/issues/11919#issuecomment-634118408

[jlperla]

Perfect, thanks!