Notebooks code cleanup

[roblourens]

• Review internal APIs
  • NotebookEditorWidget
  • NotebookViewModel
  • NotebookTextModel#applyEdits
• More work on notebookExecutionService.ts (Notebook cell execution isn't managed in the renderer #125668)
• Clean up cellRenderer.ts
• CSS cleanup Clean up notebook CSS #140133

[rebornix]

My wish list of internal API of the notebook editor component:

• No .viewModel usage in contrib
  • This means we would need API on NotebookEditorWidget
• Unify mulit-selection aware notebook actions

[roblourens]

I think probably everything except my cellRenderer task is done? Anything else you plan to do?

[rebornix]

Yeah, the only thing left is polishing cell renderer. Let's finish that next month.

[rebornix]

Potential issues found while refactoring the cell renderer:

• CSS for dnd doesn't work for markdown cell as it's webview based

  vscode/src/vs/workbench/contrib/notebook/browser/view/renderers/cellRenderer.ts

  Lines 162 to 166 in 57f6be8

  	if (element.dragging) {
  	templateData.container.classList.add(DRAGGING_CLASS);
  	} else {
  	templateData.container.classList.remove(DRAGGING_CLASS);
  	}

  . Suggestion for fixing this would be moving dnd completely out of the cellRenderer and use decoration API which can work in both main and iframe @roblourens